iOS UIImageRenderingMode

UIImage 的三种渲染模式:

UIImageRenderingModeAutomatic 

根据图片的使用环境和所处的绘图上下文自动调整渲染模式。 

UIImageRenderingModeAlwaysOriginal

始终绘制图片原始状态

UIImageRenderingModeAlwaysTemplate

 根据Tint Color绘制图片，忽略图片的颜色信息。 

用法举例:

 _registButton = [UIButton buttonWithType:UIButtonTypeSystem];

 _registButton.frame = CGRectMake(kScreenWidth - _loginButton.frame.size.width, 210, 120, 40);

[_registButton setImage:[[UIImage imageNamed:@"register_button"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal] forState:(UIControlStateNormal)];

[self addSubview:_registButton];