iOS开发UIView.h简介

1、UICoordinateSpace不同坐标空间的坐标切换

@protocol UICoordinateSpace <NSObject>
//将当前的坐标空间点转换到指定的坐标空间
- (CGPoint)convertPoint:(CGPoint)point toCoordinateSpace:(id <UICoordinateSpace>)coordinateSpace NS_AVAILABLE_IOS(8_0);
//将指定的坐标空间点转换到当前的坐标空间
- (CGPoint)convertPoint:(CGPoint)point fromCoordinateSpace:(id <UICoordinateSpace>)coordinateSpace NS_AVAILABLE_IOS(8_0);
//将当前坐标空间的矩形转换到指定的坐标空间
- (CGRect)convertRect:(CGRect)rect toCoordinateSpace:(id <UICoordinateSpace>)coordinateSpace NS_AVAILABLE_IOS(8_0);
//将指定坐标空间的矩形转换到当前的坐标空间
- (CGRect)convertRect:(CGRect)rect fromCoordinateSpace:(id <UICoordinateSpace>)coordinateSpace NS_AVAILABLE_IOS(8_0);
@end

　　举例说明：

　　1》_testView上的坐标（0，0），转换到指定屏幕坐标空间后---》坐标为（20，20）

　　2》指定屏幕坐标空间的点坐标（0，0），转换到_testView坐标空间上--》坐标为（-20，-20）

　　3》_testView坐标空间的_toView坐标为{{10，10}，{20，10}}，转换到指定主屏幕坐标空间上--》坐标为{{30，30}，{20，10}}

　　4》指定主屏幕坐标空间上坐标为{{10，10}，{20，10}}，转换到_testView坐标空间上--》坐标为{{-10，-10}，{20，10}}

 2、UIView的基本属性

@interface UIView : UIResponder <NSCoding, UIAppearance, UIAppearanceContainer, UIDynamicItem, UITraitEnvironment, UICoordinateSpace, UIFocusItem, CALayerDelegate>

#if UIKIT_DEFINE_AS_PROPERTIES
@property(class, nonatomic, readonly) Class layerClass;                        // default is [CALayer class].
#else
+ (Class)layerClass;                        // default is [CALayer class].
#endif
//初始化
- (instancetype)initWithFrame:(CGRect)frame NS_DESIGNATED_INITIALIZER;
- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder NS_DESIGNATED_INITIALIZER;

@property(nonatomic,getter=isUserInteractionEnabled) BOOL userInteractionEnabled;  // default is YES.是否可交互
@property(nonatomic)                                 NSInteger tag;                // default is 0，标记
@property(nonatomic,readonly,strong)                 CALayer  *layer;              // returns view's layer.

#if UIKIT_DEFINE_AS_PROPERTIES
@property(nonatomic,readonly) BOOL canBecomeFocused NS_AVAILABLE_IOS(9_0); // NO by default ，是否可聚焦
#else
- (BOOL)canBecomeFocused NS_AVAILABLE_IOS(9_0); // NO by default
#endif
@property (readonly, nonatomic, getter=isFocused) BOOL focused NS_AVAILABLE_IOS(9_0);//
@property (nonatomic) UISemanticContentAttribute semanticContentAttribute NS_AVAILABLE_IOS(9_0);// 内容布局方向
// 获取视图方向
+ (UIUserInterfaceLayoutDirection)userInterfaceLayoutDirectionForSemanticContentAttribute:(UISemanticContentAttribute)attribute NS_AVAILABLE_IOS(9_0);
// 相对于指定视图的视图方向
+ (UIUserInterfaceLayoutDirection)userInterfaceLayoutDirectionForSemanticContentAttribute:(UISemanticContentAttribute)semanticContentAttribute relativeToLayoutDirection:(UIUserInterfaceLayoutDirection)layoutDirection NS_AVAILABLE_IOS(10_0);
// 获取视图的布局方向
@property (readonly, nonatomic) UIUserInterfaceLayoutDirection effectiveUserInterfaceLayoutDirection NS_AVAILABLE_IOS(10_0);
@end

　　许多iOS9.0之后添加的属性，不常用也不太懂，比如semanticContentAttribute的使用：设置label的对应属性为RightToLeft，其内容是右对齐，也就是说从右向左布局！

    lable.semanticContentAttribute = UISemanticContentAttributeForceRightToLeft;

　　

3、UIViewGeometry有关view坐标

@interface UIView(UIViewGeometry)
@property(nonatomic) CGRect            frame;       // 坐标
@property(nonatomic) CGRect            bounds;      // 大小
@property(nonatomic) CGPoint           center;      // 中心点
@property(nonatomic) CGAffineTransform transform;   // 二维动画
@property(nonatomic) CGFloat           contentScaleFactor NS_AVAILABLE_IOS(4_0); //内容的缩放比例

@property(nonatomic,getter=isMultipleTouchEnabled) BOOL multipleTouchEnabled __TVOS_PROHIBITED;   // default is NO，是否支持多点触控
@property(nonatomic,getter=isExclusiveTouch) BOOL       exclusiveTouch __TVOS_PROHIBITED;         // default is NO，独占整个touch事件（防止一个界面同时点击多个Button导致响应多个方法）

- (nullable UIView *)hitTest:(CGPoint)point withEvent:(nullable UIEvent *)event;//指定点point 点击时响应指定事件 event
- (BOOL)pointInside:(CGPoint)point withEvent:(nullable UIEvent *)event;//当前事件event点击的点point是否在view上 默认YES

- (CGPoint)convertPoint:(CGPoint)point toView:(nullable UIView *)view;//将点point坐标从所在视图，转换到目标视图view获取新坐标
- (CGPoint)convertPoint:(CGPoint)point fromView:(nullable UIView *)view;//将view视图上的点point，转换到所在视图获取新坐标
- (CGRect)convertRect:(CGRect)rect toView:(nullable UIView *)view;//将rect坐标从所在视图，转换到目标视图view获取新坐标
- (CGRect)convertRect:(CGRect)rect fromView:(nullable UIView *)view;//将view视图上的rect，转换到所在视图获取新坐标

@property(nonatomic) BOOL               autoresizesSubviews; // default is YES.自动调整子视图尺寸
@property(nonatomic) UIViewAutoresizing autoresizingMask;    // default is UIViewAutoresizingNone 自动调整父视图和子视图位置、间隔

- (CGSize)sizeThatFits:(CGSize)size;     // 计算出最优的 size 但是不会改变 自己的 size
- (void)sizeToFit;                       // 计算出最优的 size 而且会改变自己的size
@end

　　特殊：exclusiveTouch设置为YES，可以防止同一个view上多个Button同时点击响应多个事件！

　　　　　坐标空间转换和UICoordinateSpace相似！

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    [[UIView appearance] setExclusiveTouch:YES];
    return YES;
}

4、UIViewHierarchy有关view添加、删除等级制度

@interface UIView(UIViewHierarchy)
@property(nullable, nonatomic,readonly) UIView       *superview;//获取父视图
@property(nonatomic,readonly,copy) NSArray<__kindof UIView *> *subviews;//获取所有子视图
@property(nullable, nonatomic,readonly) UIWindow     *window;//获取window

- (void)removeFromSuperview;//从父视图上移除
- (void)insertSubview:(UIView *)view atIndex:(NSInteger)index;//将子视图view插入到子视图数组中index位置
- (void)exchangeSubviewAtIndex:(NSInteger)index1 withSubviewAtIndex:(NSInteger)index2;//将位置index1和index2子视图互换位置
- (void)addSubview:(UIView *)view;//添加视图view
- (void)insertSubview:(UIView *)view belowSubview:(UIView *)siblingSubview;//插入子视图view在siblingSubview视图下
- (void)insertSubview:(UIView *)view aboveSubview:(UIView *)siblingSubview;//插入子视图view在siblingSubview视图上
- (void)bringSubviewToFront:(UIView *)view;//将子视图view显示在最上方
- (void)sendSubviewToBack:(UIView *)view;//将子视图view显示在最下方

- (void)didAddSubview:(UIView *)subview;//子视图添加完成调用
- (void)willRemoveSubview:(UIView *)subview;//将要移除子视图调用
- (void)willMoveToSuperview:(nullable UIView *)newSuperview;//将要移动到新父视图调用
- (void)didMoveToSuperview;//已经移动到新父视图调用
- (void)willMoveToWindow:(nullable UIWindow *)newWindow;//将要移动到新Window调用
- (void)didMoveToWindow;//已经移动到新Window调用

- (BOOL)isDescendantOfView:(UIView *)view;  // returns YES for self. view是否为子视图
- (nullable __kindof UIView *)viewWithTag:(NSInteger)tag; // 通过tag获取对应子视图
- (void)setNeedsLayout;//更新布局
- (void)layoutIfNeeded;//强制立即更新
- (void)layoutSubviews;//更新子视图frame

@property (nonatomic) UIEdgeInsets layoutMargins NS_AVAILABLE_IOS(8_0);//设置视图边距,该属性只对autolayout布局有效
@property (nonatomic) NSDirectionalEdgeInsets directionalLayoutMargins API_AVAILABLE(ios(11.0),tvos(11.0));//对layoutMargins的扩充支持Right to Left语言
@property (nonatomic) BOOL preservesSuperviewLayoutMargins NS_AVAILABLE_IOS(8_0); // default is NO 当前视图间距和父视图是否相等
@property (nonatomic) BOOL insetsLayoutMarginsFromSafeArea API_AVAILABLE(ios(11.0),tvos(11.0));  // Default: YES 控制safeAreaInsets是否加到layoutMargins上
- (void)layoutMarginsDidChange NS_AVAILABLE_IOS(8_0);//改变layoutMargins时调用
@property (nonatomic,readonly) UIEdgeInsets safeAreaInsets API_AVAILABLE(ios(11.0),tvos(11.0));//安全区域
- (void)safeAreaInsetsDidChange API_AVAILABLE(ios(11.0),tvos(11.0));//安全区域发生改变调用
@property(readonly,strong) UILayoutGuide *layoutMarginsGuide NS_AVAILABLE_IOS(9_0);//视图间距引导
@property (nonatomic, readonly, strong) UILayoutGuide *readableContentGuide  NS_AVAILABLE_IOS(9_0);//获取区域内布局引导
@property(nonatomic,readonly,strong) UILayoutGuide *safeAreaLayoutGuide API_AVAILABLE(ios(11.0),tvos(11.0));//获取安全区域引导
@end

5、UIViewRendering有关view的绘制层操作

@interface UIView(UIViewRendering)
- (void)drawRect:(CGRect)rect;//重写此方法进行绘画操作
- (void)setNeedsDisplay;//标记是否需要重绘
- (void)setNeedsDisplayInRect:(CGRect)rect;//标记指定区域是否需要重绘

@property(nonatomic)                 BOOL              clipsToBounds;              //  Default is NO. 是否裁剪超出bounds范围外视图
@property(nullable, nonatomic,copy)            UIColor          *backgroundColor; // default is nil. 背景色
@property(nonatomic)                 CGFloat           alpha;                      // default is 1.0 透明度
@property(nonatomic,getter=isOpaque) BOOL              opaque;                     // default is YES. 是否不透明
@property(nonatomic)                 BOOL              clearsContextBeforeDrawing; // default is YES. 重绘前是否清除视图内容
@property(nonatomic,getter=isHidden) BOOL              hidden;                     // default is NO. 是否隐藏
@property(nonatomic)                 UIViewContentMode contentMode;                // default is UIViewContentModeScaleToFill 填充模式
@property(nonatomic)                 CGRect            contentStretch NS_DEPRECATED_IOS(3_0,6_0) __TVOS_PROHIBITED; // animatable. default is unit rectangle {{0,0} {1,1}}. Now deprecated: please use -[UIImage resizableImageWithCapInsets:]  拉伸属性
@property(nullable, nonatomic,strong)          UIView           *maskView NS_AVAILABLE_IOS(8_0);//蒙版view
@property(null_resettable, nonatomic, strong) UIColor *tintColor NS_AVAILABLE_IOS(7_0);//
@property(nonatomic) UIViewTintAdjustmentMode tintAdjustmentMode NS_AVAILABLE_IOS(7_0);//设置tintColor的着色模式
- (void)tintColorDidChange NS_AVAILABLE_IOS(7_0);//改变tintColor调用方法
@end

　　注意：tintColor是所有UI控件都有的一个属性，系统默认是蓝色。比如创建一个系统Button就是蓝色！

　　　　   如果将这个Button放在一个view上，view的tintColor改为redColor，则这个Button就会变成redColor！

　　　　   不指定tintColor，子视图就会和父视图保持一致！

　　　　   有三种模式：和父视图一致、颜色变暗、去除父视图的设置

6、UIViewAnimation有关view的动画

@interface UIView(UIViewAnimation)
+ (void)beginAnimations:(nullable NSString *)animationID context:(nullable void *)context;  //开始动画
+ (void)commitAnimations;                                                 //提交动画
+ (void)setAnimationDelegate:(nullable id)delegate;                          // default = nil 设置动画代理
+ (void)setAnimationWillStartSelector:(nullable SEL)selector;                // default = NULL. 到那个号将要开始
+ (void)setAnimationDidStopSelector:(nullable SEL)selector;                  // default = NULL. 动画已经结束
+ (void)setAnimationDuration:(NSTimeInterval)duration;              // default = 0.2 设置动画世界
+ (void)setAnimationDelay:(NSTimeInterval)delay;                    // default = 0.0 设置动画延迟执行时间
+ (void)setAnimationStartDate:(NSDate *)startDate;                  // default = now ([NSDate date]) 设置动画块内 动画属性改变的开始时间
+ (void)setAnimationCurve:(UIViewAnimationCurve)curve;              // default = UIViewAnimationCurveEaseInOut 设置红花曲线
+ (void)setAnimationRepeatCount:(float)repeatCount;                 // default = 0.0. 设置动画重复次数
+ (void)setAnimationRepeatAutoreverses:(BOOL)repeatAutoreverses;    // default = NO. 是否自动翻转当前动画
+ (void)setAnimationBeginsFromCurrentState:(BOOL)fromCurrentState;  // default = NO. 设置动画从当前状态开始播放

+ (void)setAnimationTransition:(UIViewAnimationTransition)transition forView:(UIView *)view cache:(BOOL)cache;  // 在动画块中设置视图的过渡动画
+ (void)setAnimationsEnabled:(BOOL)enabled;                         // 是否激活动画
#if UIKIT_DEFINE_AS_PROPERTIES
@property(class, nonatomic, readonly) BOOL areAnimationsEnabled; //动画是否结束
#else
+ (BOOL)areAnimationsEnabled; //动画是否结束
#endif
+ (void)performWithoutAnimation:(void (NS_NOESCAPE ^)(void))actionsWithoutAnimation NS_AVAILABLE_IOS(7_0);// 先检查动画当前是否启用，然后禁止动画，执行block内的方法，最后重新启用动画，而且这个方法不会阻塞基于CoreAnimation的动画

//当前动画持续时间
#if UIKIT_DEFINE_AS_PROPERTIES
@property(class, nonatomic, readonly) NSTimeInterval inheritedAnimationDuration NS_AVAILABLE_IOS(9_0);
#else
+ (NSTimeInterval)inheritedAnimationDuration NS_AVAILABLE_IOS(9_0);
#endif
@end

　　举例说明：

    UIView *view = [[UIView alloc] initWithFrame:CGRectMake(10, 30, 100, 100)];
    view.backgroundColor = [UIColor redColor];
    [self.view addSubview:view];
    [UIView beginAnimations:@"view" context:(__bridge void * _Nullable)(self)];
    [UIView setAnimationDuration:1];
    [UIView setAnimationDelay:1];
    [UIView setAnimationRepeatCount:1000];
    [UIView setAnimationRepeatAutoreverses:YES];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
    [UIView setAnimationDelegate:self];
    view.center = CGPointMake(CScreenWidth-100, 80);
    [UIView commitAnimations];

7、UIViewAnimationWithBlocks有个view动画

　　基础动画：

    [UIView animateWithDuration:1 delay:1 usingSpringWithDamping:.3 initialSpringVelocity:12
                        options:UIViewAnimationOptionRepeat
                     animations:^{
                         view.center = CGPointMake(CScreenWidth-100, 80);
                     } completion:nil];

/**
 动画block
 
 @param duration 动画时间
 @param delay 延迟时间
 @param dampingRatio 弹性阻尼 0-1，越小弹性越明显
 @param velocity 初始速度>=0，越大弹动幅度越大
 @param options 动画属性枚举
 @param animations 动画内容
 @param completion 完成动画后内容
 */
+ (void)animateWithDuration:(NSTimeInterval)duration delay:(NSTimeInterval)delay options:(UIViewAnimationOptions)options animations:(void (^)(void))animations completion:(void (^ __nullable)(BOOL finished))completion NS_AVAILABLE_IOS(4_0);
+ (void)animateWithDuration:(NSTimeInterval)duration animations:(void (^)(void))animations completion:(void (^ __nullable)(BOOL finished))completion NS_AVAILABLE_IOS(4_0); // delay = 0.0, options = 0
+ (void)animateWithDuration:(NSTimeInterval)duration animations:(void (^)(void))animations NS_AVAILABLE_IOS(4_0); // delay = 0.0, options = 0, completion = NULL
+ (void)animateWithDuration:(NSTimeInterval)duration delay:(NSTimeInterval)delay usingSpringWithDamping:(CGFloat)dampingRatio initialSpringVelocity:(CGFloat)velocity options:(UIViewAnimationOptions)options animations:(void (^)(void))animations completion:(void (^ __nullable)(BOOL finished))completion NS_AVAILABLE_IOS(7_0);

　　转场动画：

    UIView *view2 = [[UIView alloc] initWithFrame:CGRectMake(0, 0, CScreenWidth, CScreenHeight)];
    view2.backgroundColor = [UIColor grayColor];
    [UIView transitionFromView:_view1 toView:view2
                      duration:1
                       options:UIViewAnimationOptionTransitionFlipFromRight
                    completion:^(BOOL finished) {
                        [self.view addSubview:view2];
                    }];

/**
 用于转场动画
 
 @param fromView 当前view
 @param toView 目标view
 @param duration 动画时间
 @param options 动画属性枚举
 @param completion 动画完成后内容
 */
+ (void)transitionWithView:(UIView *)view duration:(NSTimeInterval)duration options:(UIViewAnimationOptions)options animations:(void (^ __nullable)(void))animations completion:(void (^ __nullable)(BOOL finished))completion NS_AVAILABLE_IOS(4_0);
+ (void)transitionFromView:(UIView *)fromView toView:(UIView *)toView duration:(NSTimeInterval)duration options:(UIViewAnimationOptions)options completion:(void (^ __nullable)(BOOL finished))completion NS_AVAILABLE_IOS(4_0);

　　消失动画：缩小、模糊、消失

    [UIView performSystemAnimation:UISystemAnimationDelete
                           onViews:@[view]
                           options:UIViewAnimationOptionRepeat
                        animations:^{
                            view.center = self.view.center;
                        } completion:nil];

/**
 消失动画
 @param animation UISystemAnimationDelete只有一个枚举值
 @param views 动画的view数组
 @param options 属性枚举
 @param parallelAnimations 动画内容
 @param completion 完成动画后内容
 */
+ (void)performSystemAnimation:(UISystemAnimation)animation onViews:(NSArray<__kindof UIView *> *)views options:(UIViewAnimationOptions)options animations:(void (^ __nullable)(void))parallelAnimations completion:(void (^ __nullable)(BOOL finished))completion NS_AVAILABLE_IOS(7_0);

8、UIViewKeyframeAnimations有个view的关键帧动画

@interface UIView (UIViewKeyframeAnimations)
/**
 关键帧动画

 @param duration 动画时间
 @param delay 延迟时间
 @param options 动画类型枚举
 @param animations 动画内容
 @param completion 完成后内容
 */
+ (void)animateKeyframesWithDuration:(NSTimeInterval)duration delay:(NSTimeInterval)delay options:(UIViewKeyframeAnimationOptions)options animations:(void (^)(void))animations completion:(void (^ __nullable)(BOOL finished))completion NS_AVAILABLE_IOS(7_0);
/**
 插入关键帧

 @param frameStartTime 动画块中当前帧的开始时间比：0-1
 @param frameDuration 动画块中当前帧的动画时间比：0-1
 @param animations 动画内容
 */
+ (void)addKeyframeWithRelativeStartTime:(double)frameStartTime relativeDuration:(double)frameDuration animations:(void (^)(void))animations NS_AVAILABLE_IOS(7_0);
@end

    [UIView animateKeyframesWithDuration:2
                                   delay:1
                                 options:UIViewKeyframeAnimationOptionRepeat
                              animations:^{
                                  self->_view1.frame = CGRectMake(0, 110, 100, 200);
                              }
                              completion:nil];
    [UIView animateKeyframesWithDuration:9.0
                                   delay:0.f
                                 options:UIViewKeyframeAnimationOptionRepeat
                              animations:^{
        [UIView addKeyframeWithRelativeStartTime:0.f relativeDuration:1.0 / 4 animations:^{
            self.view1.backgroundColor = [UIColor colorWithRed:0.9475 green:0.1921 blue:0.1746 alpha:1.0];
        }];
        [UIView addKeyframeWithRelativeStartTime:1.0 / 4 relativeDuration:1.0 / 4 animations:^{
            self.view1.backgroundColor = [UIColor colorWithRed:0.1064 green:0.6052 blue:0.0334 alpha:1.0];
        }];
        [UIView addKeyframeWithRelativeStartTime:2.0 / 4 relativeDuration:1.0 / 4 animations:^{
            self.view1.backgroundColor = [UIColor colorWithRed:0.1366 green:0.3017 blue:0.8411 alpha:1.0];
        }];
        [UIView addKeyframeWithRelativeStartTime:3.0 / 4 relativeDuration:1.0 / 4 animations:^{
            self.view1.backgroundColor = [UIColor colorWithRed:0.619 green:0.037 blue:0.6719 alpha:1.0];
        }];
        [UIView addKeyframeWithRelativeStartTime:3.0 / 4 relativeDuration:1.0 / 4 animations:^{
            self.view1.backgroundColor = [UIColor redColor];
        }];
    } completion:nil];

9、UIViewGestureRecognizers有关view上的手势

@interface UIView (UIViewGestureRecognizers)
//获取view上所有手势
@property(nullable, nonatomic,copy) NSArray<__kindof UIGestureRecognizer *> *gestureRecognizers NS_AVAILABLE_IOS(3_2);
- (void)addGestureRecognizer:(UIGestureRecognizer*)gestureRecognizer NS_AVAILABLE_IOS(3_2);//添加一个手势
- (void)removeGestureRecognizer:(UIGestureRecognizer*)gestureRecognizer NS_AVAILABLE_IOS(3_2);//删除一个手势
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer NS_AVAILABLE_IOS(6_0);//开始进行手势识别时调用，返回NO不再触发手势
@end

10、UIViewMotionEffects有关UIView的运动效果

@interface UIView (UIViewMotionEffects)
- (void)addMotionEffect:(UIMotionEffect *)effect NS_AVAILABLE_IOS(7_0);//添加一个运动效果
- (void)removeMotionEffect:(UIMotionEffect *)effect NS_AVAILABLE_IOS(7_0);//移除一个运动效果
@property (copy, nonatomic) NSArray<__kindof UIMotionEffect *> *motionEffects NS_AVAILABLE_IOS(7_0);//获取所有运动效果
@end

11、UIView的其它类别

typedef NS_ENUM(NSInteger, UILayoutConstraintAxis) {
    UILayoutConstraintAxisHorizontal = 0,
    UILayoutConstraintAxisVertical = 1
};

@interface UIView (UIConstraintBasedLayoutInstallingConstraints)
@property(nonatomic,readonly) NSArray<__kindof NSLayoutConstraint *> *constraints NS_AVAILABLE_IOS(6_0);//获取所有约束
- (void)addConstraint:(NSLayoutConstraint *)constraint NS_AVAILABLE_IOS(6_0); //添加一个约束
- (void)addConstraints:(NSArray<__kindof NSLayoutConstraint *> *)constraints NS_AVAILABLE_IOS(6_0); //添加多个约束
- (void)removeConstraint:(NSLayoutConstraint *)constraint NS_AVAILABLE_IOS(6_0); //移除一个约束
- (void)removeConstraints:(NSArray<__kindof NSLayoutConstraint *> *)constraints NS_AVAILABLE_IOS(6_0); //移除多个约束
@end

@interface UIView (UIConstraintBasedLayoutCoreMethods)
- (void)updateConstraintsIfNeeded NS_AVAILABLE_IOS(6_0); //更新视图和子视图约束
- (void)updateConstraints NS_AVAILABLE_IOS(6_0) NS_REQUIRES_SUPER; //立即更新视图约束
- (BOOL)needsUpdateConstraints NS_AVAILABLE_IOS(6_0);//视图的约束是否需要更新
- (void)setNeedsUpdateConstraints NS_AVAILABLE_IOS(6_0);//设置视图的约束需要更新 调用此方法系统自动调用updateConstraints
@end

@interface UIView (UIConstraintBasedCompatibility)
@property(nonatomic) BOOL translatesAutoresizingMaskIntoConstraints NS_AVAILABLE_IOS(6_0); // Default YES 是否启用自动布局约束
#if UIKIT_DEFINE_AS_PROPERTIES//是否使用约束布局
@property(class, nonatomic, readonly) BOOL requiresConstraintBasedLayout NS_AVAILABLE_IOS(6_0);
#else
+ (BOOL)requiresConstraintBasedLayout NS_AVAILABLE_IOS(6_0);
#endif

@end
@interface UIView (UIConstraintBasedLayoutLayering)
- (CGRect)alignmentRectForFrame:(CGRect)frame NS_AVAILABLE_IOS(6_0);//返回给定视图frame的对齐矩阵
- (CGRect)frameForAlignmentRect:(CGRect)alignmentRect NS_AVAILABLE_IOS(6_0);//返回给定对齐矩阵的视图frame
#if UIKIT_DEFINE_AS_PROPERTIES//返回从视图的frame上定义的对齐矩阵的边框
@property(nonatomic, readonly) UIEdgeInsets alignmentRectInsets NS_AVAILABLE_IOS(6_0);
#else
- (UIEdgeInsets)alignmentRectInsets NS_AVAILABLE_IOS(6_0);
#endif
//返回满足基线约束条件的视图
- (UIView *)viewForBaselineLayout NS_DEPRECATED_IOS(6_0, 9_0, "Override -viewForFirstBaselineLayout or -viewForLastBaselineLayout as appropriate, instead") __TVOS_PROHIBITED;
@property(readonly,strong) UIView *viewForFirstBaselineLayout NS_AVAILABLE_IOS(9_0);//返回用于满足第一基线约束的视图
@property(readonly,strong) UIView *viewForLastBaselineLayout NS_AVAILABLE_IOS(9_0);//返回用于满足上次基线约束的视图

UIKIT_EXTERN const CGFloat UIViewNoIntrinsicMetric NS_AVAILABLE_IOS(6_0); // -1
#if UIKIT_DEFINE_AS_PROPERTIES//返回接收对象的原本大小
@property(nonatomic, readonly) CGSize intrinsicContentSize NS_AVAILABLE_IOS(6_0);
#else
- (CGSize)intrinsicContentSize NS_AVAILABLE_IOS(6_0);
#endif
- (void)invalidateIntrinsicContentSize NS_AVAILABLE_IOS(6_0); //废除视图原本内容的size
- (UILayoutPriority)contentHuggingPriorityForAxis:(UILayoutConstraintAxis)axis NS_AVAILABLE_IOS(6_0);//视图变大时返回优先级
- (void)setContentHuggingPriority:(UILayoutPriority)priority forAxis:(UILayoutConstraintAxis)axis NS_AVAILABLE_IOS(6_0);//设置阻止视图变大优先权
- (UILayoutPriority)contentCompressionResistancePriorityForAxis:(UILayoutConstraintAxis)axis NS_AVAILABLE_IOS(6_0);//视图变小时返回优先级
- (void)setContentCompressionResistancePriority:(UILayoutPriority)priority forAxis:(UILayoutConstraintAxis)axis NS_AVAILABLE_IOS(6_0);//设置阻止视图变小优先权
@end

UIKIT_EXTERN const CGSize UILayoutFittingCompressedSize NS_AVAILABLE_IOS(6_0);
UIKIT_EXTERN const CGSize UILayoutFittingExpandedSize NS_AVAILABLE_IOS(6_0);

@interface UIView (UIConstraintBasedLayoutFittingSize)
- (CGSize)systemLayoutSizeFittingSize:(CGSize)targetSize NS_AVAILABLE_IOS(6_0); //返回满足持有约束的视图的大小
- (CGSize)systemLayoutSizeFittingSize:(CGSize)targetSize withHorizontalFittingPriority:(UILayoutPriority)horizontalFittingPriority verticalFittingPriority:(UILayoutPriority)verticalFittingPriority NS_AVAILABLE_IOS(8_0);//返回满足它所包含的约束的视图的大小
@end

@interface UIView (UILayoutGuideSupport)
@property(nonatomic,readonly,copy) NSArray<__kindof UILayoutGuide *> *layoutGuides NS_AVAILABLE_IOS(9_0);//视图所有布局向导
- (void)addLayoutGuide:(UILayoutGuide *)layoutGuide NS_AVAILABLE_IOS(9_0);//添加布局向导
- (void)removeLayoutGuide:(UILayoutGuide *)layoutGuide NS_AVAILABLE_IOS(9_0);//移除布局向导
@end

@class NSLayoutXAxisAnchor,NSLayoutYAxisAnchor,NSLayoutDimension;
@interface UIView (UIViewLayoutConstraintCreation)
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *leadingAnchor NS_AVAILABLE_IOS(9_0);//前布局锚点（阿拉伯语后布局锚点）
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *trailingAnchor NS_AVAILABLE_IOS(9_0);//后布局锚点（阿拉伯语前布局锚点）
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *leftAnchor NS_AVAILABLE_IOS(9_0);//左锚点
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *rightAnchor NS_AVAILABLE_IOS(9_0);//右锚点
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *topAnchor NS_AVAILABLE_IOS(9_0);//上锚点
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *bottomAnchor NS_AVAILABLE_IOS(9_0);//下锚点
@property(nonatomic,readonly,strong) NSLayoutDimension *widthAnchor NS_AVAILABLE_IOS(9_0);//宽度
@property(nonatomic,readonly,strong) NSLayoutDimension *heightAnchor NS_AVAILABLE_IOS(9_0);//高度
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *centerXAnchor NS_AVAILABLE_IOS(9_0);//水平中心轴
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *centerYAnchor NS_AVAILABLE_IOS(9_0);//垂直中心轴
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *firstBaselineAnchor NS_AVAILABLE_IOS(9_0);//上基准线
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *lastBaselineAnchor NS_AVAILABLE_IOS(9_0);//下基准线
@end

@interface UIView (UIConstraintBasedLayoutDebugging)
- (NSArray<__kindof NSLayoutConstraint *> *)constraintsAffectingLayoutForAxis:(UILayoutConstraintAxis)axis NS_AVAILABLE_IOS(6_0);//不同方向的所有约束
#if UIKIT_DEFINE_AS_PROPERTIES//当前视图布局是否冲突
@property(nonatomic, readonly) BOOL hasAmbiguousLayout NS_AVAILABLE_IOS(6_0);
#else
- (BOOL)hasAmbiguousLayout NS_AVAILABLE_IOS(6_0);
#endif
- (void)exerciseAmbiguityInLayout NS_AVAILABLE_IOS(6_0);//用来调试约束是否可行，发布应用要删除
@end
@interface UILayoutGuide (UIConstraintBasedLayoutDebugging)
- (NSArray<__kindof NSLayoutConstraint *> *)constraintsAffectingLayoutForAxis:(UILayoutConstraintAxis)axis NS_AVAILABLE_IOS(10_0);
#if UIKIT_DEFINE_AS_PROPERTIES
@property(nonatomic, readonly) BOOL hasAmbiguousLayout NS_AVAILABLE_IOS(10_0);
#else
- (BOOL)hasAmbiguousLayout NS_AVAILABLE_IOS(10_0);
#endif
@end

@interface UIView (UIStateRestoration)
@property (nullable, nonatomic, copy) NSString *restorationIdentifier NS_AVAILABLE_IOS(6_0);//标识是否支持恢复视图状态信息
- (void) encodeRestorableStateWithCoder:(NSCoder *)coder NS_AVAILABLE_IOS(6_0);//保存视图状态信息
- (void) decodeRestorableStateWithCoder:(NSCoder *)coder NS_AVAILABLE_IOS(6_0);//恢复和保持视图状态信息
@end

@interface UIView (UISnapshotting)
- (nullable UIView *)snapshotViewAfterScreenUpdates:(BOOL)afterUpdates NS_AVAILABLE_IOS(7_0);//将当前view截取成新的view
- (nullable UIView *)resizableSnapshotViewFromRect:(CGRect)rect afterScreenUpdates:(BOOL)afterUpdates withCapInsets:(UIEdgeInsets)capInsets NS_AVAILABLE_IOS(7_0);  //缩放一个view，默认是从中心点进行缩放的
- (BOOL)drawViewHierarchyInRect:(CGRect)rect afterScreenUpdates:(BOOL)afterUpdates NS_AVAILABLE_IOS(7_0);//屏幕快照
@end