背景随机颜色和按钮点击变色

btn.backgroundColor = [UIColor colorWithRed:arc4random_uniform(255)/255.0 green:arc4random_uniform(255)/255.0 blue:arc4random_uniform(255)/255.0 alpha:1];

[button setImage:[UIImag imageNamed:@"xxx.png"]forState:UIControlStateNormal];//未按下时

[button setImage:[UIImage imageNamed:@"xxx.png"] forState:UIControlStateHighlighted];//按下时

[button setBackgroundImage:[UIImag imageNamed:@"xxx.png"]forState:UIControlStateNormal];//未按下时背景颜色

[button setBackgroundImage:[UIImage imageNamed:@"xxx.png"] forState:UIControlStateHighlighted];//按下时背景颜色