iOS手势应用举例

/**
1. 使用手势识别的四个步骤

1> 实例化手势识别
- (id)initWithTarget:(id)target action:(SEL)action;
2> 设置手势识别属性
3> 将手势识别附加到指定的视图
addGestureRecognizer

4> 编写监听方法

用代码创建一个UIImageView添加到视图，实验6种手势识别。

3. 手势说明

0> UIGestureRecognizer 所有手势识别的父类，不允许直接使用，可以用来自定义手势（建议大家不要挑战）

最常用的属性：

view： 发生手势的视图
state： 手势当前的状态，主要用于连续手势，对于离散手势一般不使用



1> UITapGestureRecognizer 点按手势(离散手势，其他手势都是连续手势)

属性：
numberOfTapsRequired 点击次数，单击双击
numberOfTouchesRequired 手指根数

2> UILongPressGestureRecognizer 长按手势

属性不建议修改

3> UIPanGestureRecognizer 拖动手势

属性：不常用
方法：
// 在视图中拖动的距离
- (CGPoint)translationInView:(UIView *)view;
// 在视图中拖动的速度，通常可用于模拟惯性，需要一些物理方面的计算
- (CGPoint)velocityInView:(UIView *)view;

4> UIPinchGestureRecognizer 捏合手势

属性：
scale 比例
velocity 捏合速度，不常用

5> UIRotationGestureRecognizer 旋转手势

属性
rotation 旋转角度
velocity 旋转速度，不常用

6> UISwipeGestureRecognizer 轻扫手势，通常添加到根视图上

属性
numberOfTouchesRequired 参与轻扫手势的手指根数
direction 轻扫的方向

提示：
1) 如果要检测几个方向的轻扫，需要分别实例化几个轻扫手势
2) 轻扫手势虽然是连续手势，但是不需要去处理UIGestureRecognizerStateChanged状态
因为是在手指离开屏幕后，该手势才被识别的

其他技巧

在if语句中，将常量放置在判断条件的左侧，可以避免因为只写了 = 出现警告，置之不理的情况！
*/

- (void)viewDidLoad
{
[super viewDidLoad];

// 0. 实例化UIImageView
UIImage *image = [UIImage imageNamed:@"001"];
UIImageView *imageView = [[UIImageView alloc]initWithImage:image];

[imageView setFrame:CGRectMake(10, 100, 300, 196)];
[self.view addSubview:imageView];

[imageView setUserInteractionEnabled:YES];

// 1. 添加点按手势
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tap:)];
// 定义双击
tap.numberOfTapsRequired = 2;
[imageView addGestureRecognizer:tap];

// 2. 添加长按手势
UILongPressGestureRecognizer *longTap = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longTap:)];
[imageView addGestureRecognizer:longTap];

// 3. 拖动手势
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];

[imageView addGestureRecognizer:pan];

// 4. 捏合手势
UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinch:)];
[imageView addGestureRecognizer:pinch];

// 5. 旋转手势
UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotate:)];
[imageView addGestureRecognizer:rotation];

// 6. 轻扫手势
// 如果要做清扫手势，需要分别实例化4个方向的手势
UISwipeGestureRecognizer *swipeUp = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe:)];

swipeUp.direction = UISwipeGestureRecognizerDirectionUp | UISwipeGestureRecognizerDirectionDown | UISwipeGestureRecognizerDirectionLeft | UISwipeGestureRecognizerDirectionRight;

[self.view addGestureRecognizer:swipeUp];

// UISwipeGestureRecognizer *swipeDown = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe:)];
// swipeDown.direction = UISwipeGestureRecognizerDirectionDown;
// [self.view addGestureRecognizer:swipeDown];
//
// UISwipeGestureRecognizer *swipeLeft = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe:)];
// swipeLeft.direction = UISwipeGestureRecognizerDirectionLeft;
// [self.view addGestureRecognizer:swipeLeft];
//
// UISwipeGestureRecognizer *swipeRight = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe:)];
// swipeRight.direction = UISwipeGestureRecognizerDirectionRight;
// [self.view addGestureRecognizer:swipeRight];
}

#pragma mark - 点按手势
- (void)tap:(UITapGestureRecognizer *)recognizer
{
// 双击放大图片
UIImageView *imageView = (UIImageView *)recognizer.view;

[UIView animateWithDuration:0.8f animations:^{
[imageView setTransform:CGAffineTransformScale(imageView.transform, 2.0, 2.0)];
} completion:^(BOOL finished) {
[UIView animateWithDuration:0.5f animations:^{
[imageView setTransform:CGAffineTransformScale(imageView.transform, 0.5, 0.5)];
}];
}];
}

#pragma mark - 长按手势
- (void)longTap:(UILongPressGestureRecognizer *)recognizer
{
NSLog(@"长按");
// 长按旋转图片
// 开始长按
// 在形变时，iOS采取就近原则旋转，如果不能按照希望的方向旋转，可以增加一些修正值，例如0.01
// 直接通过形变属性，要实现一次性转一圈，比较困难，可以分两次进行
if (UIGestureRecognizerStateBegan == recognizer.state) {
[UIView animateWithDuration:0.8f animations:^{
[recognizer.view setTransform:CGAffineTransformRotate(recognizer.view.transform, M_PI - 0.01)];
}];
} else if (UIGestureRecognizerStateEnded == recognizer.state) {
[UIView animateWithDuration:0.8f animations:^{
[recognizer.view setTransform:CGAffineTransformRotate(recognizer.view.transform, M_PI - 0.01)];
} completion:^(BOOL finished) {
// 清除所有的形变属性
[recognizer.view setTransform:CGAffineTransformIdentity];
}];
}
}

#pragma mark - 拖动
- (void)pan:(UIPanGestureRecognizer *)recognizer
{
CGPoint translation = [recognizer translationInView:self.view];

// 让图像根据手指移动
if (UIGestureRecognizerStateChanged == recognizer.state) {
// 形变参数，有Make的时候，是相对初始位置计算的
// 没有Make是递增修改形变的
[recognizer.view setTransform:CGAffineTransformTranslate(recognizer.view.transform, translation.x, translation.y)];

// 拖动手指中的平移距离是相对于初始位置，如果使用CGAffineTransformTranslate累加形变方法
// 需要在每次位移之后，重置recognizer的位移量，就是将位移量清零
[recognizer setTranslation:CGPointZero inView:recognizer.view];
}
}

#pragma mark - 捏合
- (void)pinch:(UIPinchGestureRecognizer *)recognizer
{
// 调整图像的显示比例
if (UIGestureRecognizerStateChanged == recognizer.state) {

// 等比例缩放
[recognizer.view setTransform:CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale)];

// 在设置累加形变参数时，需要充值手势的缩放比例
recognizer.scale = 1.0f;
}
}

#pragma mark - 旋转
- (void)rotate:(UIRotationGestureRecognizer *)recognizer
{
if (UIGestureRecognizerStateChanged == recognizer.state) {
recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);

// 重置旋转量
recognizer.rotation = 0.0f;
}
}

#pragma mark - 轻扫
- (void)swipe:(UISwipeGestureRecognizer *)recognizer
{
//NSLog(@"%d", recognizer.direction);
if (UISwipeGestureRecognizerDirectionDown == recognizer.direction) {
NSLog(@"向下");
} else if (UISwipeGestureRecognizerDirectionUp == recognizer.direction) {
NSLog(@"向上");
} else if (UISwipeGestureRecognizerDirectionLeft == recognizer.direction) {
NSLog(@"向左");
} else if (UISwipeGestureRecognizerDirectionRight == recognizer.direction) {
NSLog(@"向右");
}
}