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 onlyUIImage* 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 sizeNSArray* 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 onlyUIGraphicsBeginImageContextWithOptions(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