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];