UIButton的resizableImageWithCapInsets使用解析--拉伸模式，通过拉伸UIEdgeInsets指定的矩形区域来填充图片

/*
UIImageResizingModeTile    ：平铺模式，通过重复显示UIEdgeInsets指定的矩形区域来填充图片
*/
UIButton *button1    = [[UIButton alloc] initWithFrame:CGRectMake(65, 250, 202, 29)];
UIImage *norImage1   = [UIImage imageNamed:@"normal"];
norImage1            = [norImage1 resizableImageWithCapInsets:UIEdgeInsetsMake(2, 2, 2, 2)
resizingMode:UIImageResizingModeTile];
[button1 setBackgroundImage:norImage1 forState:UIControlStateNormal];
[self.view addSubview:button1];

/*
UIImageResizingModeStretch ：拉伸模式，通过拉伸UIEdgeInsets指定的矩形区域来填充图片
*/
UIButton *button2    = [[UIButton alloc] initWithFrame:CGRectMake(65, 300, 202, 29)];
UIImage *norImage2   = [UIImage imageNamed:@"normal"];
norImage2            = [norImage2 resizableImageWithCapInsets:UIEdgeInsetsMake(2, 2, 2, 2)
resizingMode:UIImageResizingModeStretch];
[button2 setBackgroundImage:norImage2 forState:UIControlStateNormal];
[self.view addSubview:button2];
}