1、写了一个小Demo，实现上下移动的效果图：

主要代码如下：

- (IBAction)upChange:(id)sender {

if (typeView == down) {

[self.downBtn setHidden:NO];

[self.upBtn setHidden:NO];

[UIView animateWithDuration:0.5 animations:^{

self.upView.center = CGPointMake(self.upView.center.x, 0);

self.downView.center = CGPointMake(self.downView.center.x, (self.upView.frame.size.height+self.downView.frame.size.height)/2);

}];

typeView = middle;

}else if(typeView == middle){

[self.downBtn setHidden:NO];

[self.upBtn setHidden:YES];

[UIView animateWithDuration:0.5 animations:^{

self.upView.center = CGPointMake(self.upView.center.x, -(self.upView.frame.size.height/2));

self.downView.center = CGPointMake(self.downView.center.x, self.downView.frame.size.height/2);

}];

typeView = up;

}

}

- (IBAction)downChange:(id)sender {

if (typeView == middle) {

[self.downBtn setHidden:YES];

[self.upBtn setHidden:NO];

[UIView animateWithDuration:0.5 animations:^{

self.upView.center = CGPointMake(self.upView.center.x, self.upView.frame.size.height/2);

self.downView.center = CGPointMake(self.downView.center.x, self.upView.frame.size.height+self.downView.frame.size.height/2);

}];

typeView = down;

}else if(typeView == up)

{

[self.downBtn setHidden:NO];

[self.upBtn setHidden:NO];

[UIView animateWithDuration:0.5 animations:^{

self.upView.center = CGPointMake(self.upView.center.x, 0);

self.downView.center = CGPointMake(self.downView.center.x, (self.upView.frame.size.height+self.downView.frame.size.height)/2);

}];

typeView = middle;

}

}

这是主要的代码，另外还有一些需要注意的一些小细，如你的两个view的大小，需要计算出精确位置。

下面开始学习[UIView animateWithDuration]方法的使用：

函数原型：

+ (void)animateWithDuration:(NSTimeInterval)duration animations:(void (^)(void))animations __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_4_0); // delay = 0.0, options = 0, completion = NULL

duration：动画持续时间

animations：该代码儿块中是所有view要完成的动画的所有属性的定义;

还有另外两个函数：

+ (void)animateWithDuration:(NSTimeInterval)duration delay:(NSTimeInterval)delay options:(UIViewAnimationOptions)options animations:(void (^)(void))animations completion:(void (^)(BOOL finished))completion __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_4_0);

+ (void)animateWithDuration:(NSTimeInterval)duration animations:(void (^)(void))animations completion:(void (^)(BOOL finished))completion__OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_4_0);// delay = 0.0, options = 0

options:是动画执行的选项

completion：是动画完成以后所要执行的代码块儿。

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