iOS改变UIImageView的image时添加渐变,平滑改变图片

当改变UIImageView的image属性时，UI会立刻从一张图片切换到另一张图片，显得十分生硬，本文记录如何为改变UIImageView的image属性时加入淡入淡出的效果。

现在有四张UIImage，初始化后将其存入数组中:

self.imgs
= @[[UIImage
imageNamed:@"bg01"],
[UIImage
imageNamed:@"bg02"],
[UIImage
imageNamed:@"bg03"],
[UIImage
imageNamed:@"bg04"]];self.imageView.image
= self.imgs[0];

有一按钮，其事件如下:

-(IBAction)switchImg:(id)sender
{}

现在填充其实现来完成UIImageView改变image时加入1秒的淡入淡出

方法1. 使用

CATransition

CATransition *transition
= [CATransition animation];

transition.type
= kCATransitionFade;

transition.duration
= 1.0f;

transition.timingFunction
= [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];

[self.imageView.layer
addAnimation:transition forKey:nil];

UIImage *currentImage
= self.imageView.image;

NSUInteger index = [self.imgs
indexOfObject:currentImage];

index = (index +1)
% [self.imgs
count];

self.imageView.image
= self.imgs[index];

方法2. 使用UIView类方法

transitionWithView

UIImage
*currentImage = self.imageView.image;

NSUInteger index = [self.imgs indexOfObject:currentImage];index = (index + 1)
% [self.imgs
count];

[UIView
transitionWithView:self.imageView
duration:1
options:UIViewAnimationOptionTransitionCrossDissolve animations:^{

self.imageView.image = self.imgs[index];} completion:nil];