iOS UIView的简单渐变效果

这里主要用到了ios4.0以后 UIView的类方法 animateWithDuration:

函数原型包括以下类方法

+ (void)animateWithDuration:(NSTimeInterval)duration animations:(void (^)(void))animations
+ (void)animateWithDuration:(NSTimeInterval)duration animations:(void (^)(void))animations completion:(void (^)(BOOL finished))completion
+ (void)animateWithDuration:(NSTimeInterval)duration delay:(NSTimeInterval)delay options:(UIViewAnimationOptions)options animations:(void (^)(void))animations completion:(void (^)(BOOL finished))completion

参数介绍

duration:动画的持续时间

annimations:动画的实体

completion:annimations执行完后立即执行的代码

options:枚举值，动画执行期间的一些设置

下面是可以设置动画效果的属性：

• frame
• bounds
• center
• transform
• alpha
• backgroundColor
• contentStretch

动画效果的代码块可以有多个属性

[UIView animateWithDuration:0.5 animations:^{
            view.alpha = 0;
            view.frame = CGRectMake(0, 0, 100, 100);
        }];