UIActivityIndicatorView
self.activity.color = [UIColor yellowColor];
self.activity.backgroundColor = [UIColor colorWithWhite:0.2 alpha:0.4];
self.activity.layer.cornerRadius = 10;
CGRect f = self.activity.bounds;
f.size.width += 10;
f.size.height += 10;
self.activity.bounds = f;
UIProgressView
在 iOS6 一下，一个UIProgressView 类似于下面，高度是根据progressview的类型来自动设置的（标准是9），即使我们设置了也没有效果。
我们可以自定义UIProgressView的外观，为了自定义颜色，可以设置 progressTintColor，trackTintColor；为了自定义图片，可以设置progressImage，trackImage，这个图片会被拉伸来填充合适的范围，所以一般是提供一个高度为9的可拉伸的图片：
UIGraphicsBeginImageContextWithOptions(CGSizeMake(9,9), NO, 0);
CGContextRef con = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(con, [UIColor blackColor].CGColor);
CGContextMoveToPoint(con, 0, 4.5);
CGContextAddLineToPoint(con, 4.5, 9);
CGContextAddLineToPoint(con, 9, 4.5);
CGContextAddLineToPoint(con, 4.5, 0);
CGContextClosePath(con);
CGPathRef p = CGContextCopyPath(con);
CGContextFillPath(con);
UIImage* im = UIGraphicsGetImageFromCurrentImageContext();
CGContextSetFillColorWithColor(con, [UIColor whiteColor].CGColor);
CGContextAddPath(con, p);
CGContextFillPath(con);
UIImage* im2 = UIGraphicsGetImageFromCurrentImageContext();
CGPathRelease(p);
UIGraphicsEndImageContext();
im = [im resizableImageWithCapInsets:UIEdgeInsetsMake(4, 4, 4, 4)
resizingMode:UIImageResizingModeStretch];
im2 = [im2 resizableImageWithCapInsets:UIEdgeInsetsMake(4, 4, 4, 4)
resizingMode:UIImageResizingModeStretch];
prog.trackImage = im;
prog.progressImage = im2;
为了进一步的自定义，我们可以：
- (void)drawRect:(CGRect)rect {
CGContextRef c = UIGraphicsGetCurrentContext();
[[UIColor whiteColor] set];
CGFloat ins = 2.0;
CGRect r = CGRectInset(self.bounds, ins, ins);
CGFloat radius = r.size.height / 2.0;
CGMutablePathRef path = CGPathCreateMutable();
CGPathMoveToPoint(path, nil, CGRectGetMaxX(r)-radius, ins);
CGPathAddArc(path, nil,
radius+ins, radius+ins, radius, -M_PI/2.0, M_PI/2.0, true);
CGPathAddArc(path, nil,
CGRectGetMaxX(r)-radius, radius+ins, radius,
M_PI/2.0, -M_PI/2.0, true);
CGPathCloseSubpath(path);
CGContextAddPath(c, path);
CGContextSetLineWidth(c, 2);
CGContextStrokePath(c);
CGContextAddPath(c, path);
CGContextClip(c);
CGContextFillRect(c, CGRectMake(
r.origin.x, r.origin.y, r.size.width * self.value, r.size.height));
}
效果如下图：
UISwitch
一个 switch只有一种尺寸（通常是79x27），我们不能设置它的大小。从iOS 5开始，我们可以设置一个switch的onTintColor，从iOS 6开始，我们可以设置一个switch的tintColor和thumbTintColor。
iOS 6 开始，也允许你设置一个switch的onImage和 offImage，意味着你可以改变这个switch里面的文字：
UIGraphicsBeginImageContextWithOptions(CGSizeMake(79,27), NO, 0);
[[UIColor blackColor] setFill];
UIBezierPath* p = [UIBezierPath bezierPathWithRect:CGRectMake(0,0,79,27)];
[p fill];
NSMutableParagraphStyle* para = [NSMutableParagraphStyle new];
para.alignment = NSTextAlignmentCenter;
NSAttributedString* att =
[[NSAttributedString alloc] initWithString:@"YES" attributes:
@{
NSFontAttributeName:[UIFont fontWithName:@"GillSans-Bold" size:16],
NSForegroundColorAttributeName:[UIColor whiteColor],
NSParagraphStyleAttributeName:para
}];
[att drawInRect:CGRectMake(0,5,79,22)];
UIImage* im = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
self.sw2.onImage = im;
效果如下图：
UISegmentedControl
我们可以自定义UISegmentedControl的分割图片和每个选项的图片：
// background, set desired height but make width resizable
// sufficient to set for Normal only
UIImage* image = [UIImage imageNamed: @"linen.png"];
CGFloat w = 100;
CGFloat h = 60;
UIGraphicsBeginImageContextWithOptions(CGSizeMake(w,h), NO, 0);
[image drawInRect:CGRectMake(0,0,w,h)];
UIImage* image2 = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImage* image3 =
[image2 resizableImageWithCapInsets:UIEdgeInsetsMake(0,10,0,10)
resizingMode:UIImageResizingModeStretch];
[self.seg setBackgroundImage:image3 forState:UIControlStateNormal
barMetrics:UIBarMetricsDefault];
// segment images, redraw at final size
NSArray* pep = @[@"manny.jpg", @"moe.jpg", @"jack.jpg"];
for (int i = 0; i < 3; i++) {
UIImage* image = [UIImage imageNamed: pep[i]];
UIGraphicsBeginImageContextWithOptions(CGSizeMake(30,30), NO, 0);
[image drawInRect:CGRectMake(0,0,30,30)];
UIImage* image2 = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[self.seg setImage:image2 forSegmentAtIndex:i];
}
// divider, set at desired width, sufficient to set for Normal only
UIGraphicsBeginImageContextWithOptions(CGSizeMake(1,10), NO, 0);
[[UIColor whiteColor] set];
CGContextFillRect(UIGraphicsGetCurrentContext(), CGRectMake(0,0,1,10));
UIImage* div = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[self.seg setDividerImage:div
forLeftSegmentState:UIControlStateNormal
rightSegmentState:UIControlStateNormal
barMetrics:UIBarMetricsDefault];
Custom Controls
一个UIControl 类实现了一些触摸追踪的方法，你可以在子类中重写这些方法来实现自定义控件：
-
beginTrackingWithTouch:withEvent:
-
continueTrackingWithTouch:withEvent:
-
endTrackingWithTouch:withEvent:
-
cancelTrackingWithEvent:
-
tracking (property)
-
touchInside (property)
这些触摸追踪方法虽然不是手势识别的更高层次封装，但至少比UIResponse 的touches...方法高一级。
下面我们创建一个自定义的控件，一个UIControl的子类 MyKnob：
它有一个最小和最大的旋转角度，还有一个CGFloat类型的angle属性和一个CGFloat类型的实例变量 _initialAngle，我们会在旋转时用到。因为一个UIControl是一个UIView，它可以绘制自身，我们可以绘制一张图片：
- (void) drawRect:(CGRect)rect {
UIImage* knob = [UIImage imageNamed:@"knob.png"];
[knob drawInRect:rect];
}
我们需要一个实用的函数，用于将触摸的直角坐标转到极坐标，提供一个需要旋转的角度给我们的视图：
static CGFloat pToA (UITouch* touch, UIView* self) {
CGPoint loc = [touch locationInView: self];
CGPoint c = CGPointMake(CGRectGetMidX(self.bounds),
CGRectGetMidY(self.bounds));
return atan2(loc.y - c.y, loc.x - c.x);
}
现在我们可以准备重写追踪方法：
- (BOOL) beginTrackingWithTouch:(UITouch*)touch withEvent:(UIEvent*)event {
self->_initialAngle = pToA(touch, self);
return YES;
}
- (BOOL) continueTrackingWithTouch:(UITouch*)touch withEvent:(UIEvent*)event {
CGFloat ang = pToA(touch, self);
ang -= self->_initialAngle;
CGFloat absoluteAngle = self->_angle + ang;
if (absoluteAngle < 0) {
self.transform = CGAffineTransformIdentity;
self->_angle = 0;
[self sendActionsForControlEvents:UIControlEventValueChanged];
return NO;
}
if (absoluteAngle > 5) {
self.transform = CGAffineTransformMakeRotation(5);
self->_angle = 5;
[self sendActionsForControlEvents:UIControlEventValueChanged];
return NO;
}
self.transform = CGAffineTransformRotate(self.transform, ang);
self->_angle = absoluteAngle;
if (self->continuous)
[self sendActionsForControlEvents:UIControlEventValueChanged];
return YES;
}
- (void) endTrackingWithTouch:(UITouch *)touch withEvent:(UIEvent *)event {
[self sendActionsForControlEvents:UIControlEventValueChanged];
}
- (void) setAngle: (CGFloat) ang {
if (ang < 0)
ang = 0;
if (ang > 5)
ang = 5;
self.transform = CGAffineTransformMakeRotation(ang);
self->_angle = ang;
}
Appearance Proxy
外观代理给了我们一种设置控件全局样式的很方便的方式。这个代理有两个类方法：
appearance
appearanceWhenContainedIn:
设置一种例外
[[UIBarButtonItem appearance] setTintColor: [UIColor myGolden]];
表示通常情况下，一个 bar button item 应该是myGolden颜色
[[UIBarButtonItem appearanceWhenContainedIn: [UIToolbar class], nil]
setTintColor: [UIColor myPaler]];
表示bar button item 在 一个toolbar上时，应该是myPaler颜色，其它的按照上面的规定。
[[UIBarButtonItem appearanceWhenContainedIn:
[UIToolbar class], [DrillViewController class], nil]
setTintColor: [UIColor myGolden]];
表示bar button item 在一个toolbar上，同时有属于DrillViewController的视图时，应该是myGolden颜色，其它的按照上面的规定。
这个外观代理是一个id类型，所以你可以发送任何响应的消息，但是如果你发送给一个没有定义为UI_APPEARANCE_SELECTOR的消息给一个类，编译时不会报错，但是运行时会崩溃。所以，我们一般的写法不是：
[[UIBarButtonItem appearance] setTintColor: [UIColor brownColor]]; // 不严谨
而是：
((UIBarButtonItem*)[UIBarButtonItem appearance]).tintColor =
[UIColor brownColor]; // 推荐