图片的拉伸

//创建按钮

UIButton *btn=[[UIButton
alloc]init];
btn.frame=CGRectMake(50,
450, 350,
60);

UIImage *img=[UIImage
imageNamed:@"blueButton.png"];

//给返回一张经过处理后的拉升的图片

//上左下右各15个像素点不参与拉升，中间部分随便拉升

img=[img resizableImageWithCapInsets:UIEdgeInsetsMake(15,
15,
15, 15)];

[btn setBackgroundImage:img
forState:UIControlStateHighlighted];

//给按钮添加点击事件

[btn addTarget:self
action:@selector(btnPressed:)
forControlEvents:UIControlEventTouchUpInside];
[self.view
addSubview:btn];

//开启定时器

t=[NSTimer
scheduledTimerWithTimeInterval:0.5
target:self
selector:@selector(updateColor:)
userInfo:nil
repeats:YES];