该文章阅读的SDWebImage的版本为4.3.3。
该类是负责图像加载完成后在控件上的展示动画。
1.公共类型定义
/**
定义动画选项
*/
typedef UIViewAnimationOptions SDWebImageAnimationOptions;
复制代码/**
用于动画开始之前要执行的代码块
*/
typedef void (^SDWebImageTransitionPreparesBlock)(__kindof UIView * _Nonnull view, UIImage * _Nullable image, NSData * _Nullable imageData, SDImageCacheType cacheType, NSURL * _Nullable imageURL);
复制代码/**
用于控制展示动画的代码块
*/
typedef void (^SDWebImageTransitionAnimationsBlock)(__kindof UIView * _Nonnull view, UIImage * _Nullable image);
复制代码/**
用于动画结束后要执行的代码块
*/
typedef void (^SDWebImageTransitionCompletionBlock)(BOOL finished);
复制代码2.公共属性
/**
默认情况下，我们将图像设置为动画开头的视图。可以选择禁用此功能并提供自定义设置图像处理方法
*/
@property (nonatomic, assign) BOOL avoidAutoSetImage;
复制代码/**
动画的持续时间，以秒为单位。 默认为0.5秒。
*/
@property (nonatomic, assign) NSTimeInterval duration;
复制代码/**
用于macOS上的计时功能
*/
@property (nonatomic, strong, nullable) CAMediaTimingFunction *timingFunction NS_AVAILABLE_MAC(10_7);
复制代码/**
动画选项
*/
@property (nonatomic, assign) SDWebImageAnimationOptions animationOptions;
复制代码/**
动画开始前所要执行的代码块
*/
@property (nonatomic, copy, nullable) SDWebImageTransitionPreparesBlock prepares;
复制代码/**
动画代码块
*/
@property (nonatomic, copy, nullable) SDWebImageTransitionAnimationsBlock animations;
复制代码/**
动画结束后所要执行的代码块
*/
@property (nonatomic, copy, nullable) SDWebImageTransitionCompletionBlock completion;
复制代码3.Conveniences分类
这个分类用于快速创建动画。
3.1. 公共属性
调用不同的类属性获取不同的动画效果
@property (nonatomic, class, nonnull, readonly) SDWebImageTransition *fadeTransition;
@property (nonatomic, class, nonnull, readonly) SDWebImageTransition *flipFromLeftTransition;
@property (nonatomic, class, nonnull, readonly) SDWebImageTransition *flipFromRightTransition;
@property (nonatomic, class, nonnull, readonly) SDWebImageTransition *flipFromTopTransition;
@property (nonatomic, class, nonnull, readonly) SDWebImageTransition *flipFromBottomTransition;
@property (nonatomic, class, nonnull, readonly) SDWebImageTransition *curlUpTransition;
@property (nonatomic, class, nonnull, readonly) SDWebImageTransition *curlDownTransition;
复制代码3.2.公共方法
如果类属性不可用，就调用类方法类获取不同的动画效果
+ (nonnull instancetype)fadeTransition;
+ (nonnull instancetype)flipFromLeftTransition;
+ (nonnull instancetype)flipFromRightTransition;
+ (nonnull instancetype)flipFromTopTransition;
+ (nonnull instancetype)flipFromBottomTransition;
+ (nonnull instancetype)curlUpTransition;
+ (nonnull instancetype)curlDownTransition;
复制代码3.3.实现
创建不同的动画并兼容macOS
+ (SDWebImageTransition *)fadeTransition {
SDWebImageTransition *transition = [SDWebImageTransition new];
#if SD_UIKIT
transition.animationOptions = UIViewAnimationOptionTransitionCrossDissolve;
#else
transition.animations = ^(__kindof NSView * _Nonnull view, NSImage * _Nullable image) {
CATransition *trans = [CATransition animation];
trans.type = kCATransitionFade;
[view.layer addAnimation:trans forKey:kCATransition];
};
#endif
return transition;
}
+ (SDWebImageTransition *)flipFromLeftTransition {
SDWebImageTransition *transition = [SDWebImageTransition new];
#if SD_UIKIT
transition.animationOptions = UIViewAnimationOptionTransitionFlipFromLeft;
#else
transition.animations = ^(__kindof NSView * _Nonnull view, NSImage * _Nullable image) {
CATransition *trans = [CATransition animation];
trans.type = kCATransitionPush;
trans.subtype = kCATransitionFromLeft;
[view.layer addAnimation:trans forKey:kCATransition];
};
#endif
return transition;
}
+ (SDWebImageTransition *)flipFromRightTransition {
SDWebImageTransition *transition = [SDWebImageTransition new];
#if SD_UIKIT
transition.animationOptions = UIViewAnimationOptionTransitionFlipFromRight;
#else
transition.animations = ^(__kindof NSView * _Nonnull view, NSImage * _Nullable image) {
CATransition *trans = [CATransition animation];
trans.type = kCATransitionPush;
trans.subtype = kCATransitionFromRight;
[view.layer addAnimation:trans forKey:kCATransition];
};
#endif
return transition;
}
+ (SDWebImageTransition *)flipFromTopTransition {
SDWebImageTransition *transition = [SDWebImageTransition new];
#if SD_UIKIT
transition.animationOptions = UIViewAnimationOptionTransitionFlipFromTop;
#else
transition.animations = ^(__kindof NSView * _Nonnull view, NSImage * _Nullable image) {
CATransition *trans = [CATransition animation];
trans.type = kCATransitionPush;
trans.subtype = kCATransitionFromTop;
[view.layer addAnimation:trans forKey:kCATransition];
};
#endif
return transition;
}
+ (SDWebImageTransition *)flipFromBottomTransition {
SDWebImageTransition *transition = [SDWebImageTransition new];
#if SD_UIKIT
transition.animationOptions = UIViewAnimationOptionTransitionFlipFromBottom;
#else
transition.animations = ^(__kindof NSView * _Nonnull view, NSImage * _Nullable image) {
CATransition *trans = [CATransition animation];
trans.type = kCATransitionPush;
trans.subtype = kCATransitionFromBottom;
[view.layer addAnimation:trans forKey:kCATransition];
};
#endif
return transition;
}
+ (SDWebImageTransition *)curlUpTransition {
SDWebImageTransition *transition = [SDWebImageTransition new];
#if SD_UIKIT
transition.animationOptions = UIViewAnimationOptionTransitionCurlUp;
#else
transition.animations = ^(__kindof NSView * _Nonnull view, NSImage * _Nullable image) {
CATransition *trans = [CATransition animation];
trans.type = kCATransitionReveal;
trans.subtype = kCATransitionFromTop;
[view.layer addAnimation:trans forKey:kCATransition];
};
#endif
return transition;
}
+ (SDWebImageTransition *)curlDownTransition {
SDWebImageTransition *transition = [SDWebImageTransition new];
#if SD_UIKIT
transition.animationOptions = UIViewAnimationOptionTransitionCurlDown;
#else
transition.animations = ^(__kindof NSView * _Nonnull view, NSImage * _Nullable image) {
CATransition *trans = [CATransition animation];
trans.type = kCATransitionReveal;
trans.subtype = kCATransitionFromBottom;
[view.layer addAnimation:trans forKey:kCATransition];
};
#endif
return transition;
}
复制代码4.实现
实现中只做做了在初始化方法中设置默认展示时间为0.5秒
- (instancetype)init {
self = [super init];
if (self) {
self.duration = 0.5;
}
return self;
}
复制代码5.总结
这个类的总结也没啥好说的，就是帮助创建动画的类。
值得说的一点是，有一个属性关键字class，是Xcode 8中添加的，我对这个关键字的理解是：这个关键字用于声明一个“类属性”，平常我们声明的都是“对象属性”，可以类比于“类方法”和“对象方法”的关系进行理解。使用了这个关键字的属性，需要声明静态变量保存，需要手写getter和setter。在使用时，这个类属性相当于一个类内的静态全局变量，也可以类比成一个单例对象的对象属性，即这个类属性在这个类内是共享的。想要了解更多可以看这篇文章：Swift 3.0 令人兴奋，但Objective-C也有小改进--Objective-C的类属性
源码阅读系列：SDWebImage
源码阅读：SDWebImage（一）——从使用入手
源码阅读：SDWebImage（二）——SDWebImageCompat
源码阅读：SDWebImage（三）——NSData+ImageContentType
源码阅读：SDWebImage（四）——SDWebImageCoder
源码阅读：SDWebImage（五）——SDWebImageFrame
源码阅读：SDWebImage（六）——SDWebImageCoderHelper
源码阅读：SDWebImage（七）——SDWebImageImageIOCoder
源码阅读：SDWebImage（八）——SDWebImageGIFCoder
源码阅读：SDWebImage（九）——SDWebImageCodersManager
源码阅读：SDWebImage（十）——SDImageCacheConfig
源码阅读：SDWebImage（十一）——SDImageCache
源码阅读：SDWebImage（十二）——SDWebImageDownloaderOperation
源码阅读：SDWebImage（十三）——SDWebImageDownloader
源码阅读：SDWebImage（十四）——SDWebImageManager
源码阅读：SDWebImage（十五）——SDWebImagePrefetcher
源码阅读：SDWebImage（十六）——SDWebImageTransition
源码阅读：SDWebImage（十七）——UIView+WebCacheOperation
源码阅读：SDWebImage（十八）——UIView+WebCache
源码阅读：SDWebImage（十九）——UIImage+ForceDecode/UIImage+GIF/UIImage+MultiFormat
源码阅读：SDWebImage（二十）——UIButton+WebCache
源码阅读：SDWebImage（二十一）——UIImageView+WebCache/UIImageView+HighlightedWebCache