表示一下对原作者的崇敬之情
YYWebImage是大神郭的框架,专门用来做图片下载的...相对于每次都要SDWebImage+FLAnimatedImage来说,只导入一个YYWebImage.h还是相当方便的(额..就算是比较方便吧..谁没事老导框架玩..)
基本用法
1.从 URL 加载图片
// 加载网络图片
imageView.yy_imageURL = [NSURL URLWithString:@"http://github.com/logo.png"];
// 加载本地图片
imageView.yy_imageURL = [NSURL fileURLWithPath:@"/tmp/logo.png"];
2.加载动图
// 只需要把 `UIImageView` 替换为 `YYAnimatedImageView` 即可。
UIImageView *imageView = [YYAnimatedImageView new];
imageView.yy_imageURL = [NSURL URLWithString:@"http://github.com/ani.webp"];
3.渐进式图片加载
// 渐进式:边下载边显示
[imageView yy_setImageWithURL:url options:YYWebImageOptionProgressive];
// 渐进式加载,增加模糊效果和渐变动画 (见本页最上方的GIF演示)
[imageView yy_setImageWithURL:url options:YYWebImageOptionProgressiveBlur | YYWebImageOptionSetImageWithFadeAnimation];
4.加载、处理图片
// 1. 下载图片
// 2. 获得图片下载进度
// 3. 调整图片大小、加圆角
// 4. 显示图片时增加一个淡入动画,以获得更好的用户体验
[imageView yy_setImageWithURL:url
placeholder:nil
options:YYWebImageOptionSetImageWithFadeAnimation
progress:^(NSInteger receivedSize, NSInteger expectedSize) {
progress = (float)receivedSize / expectedSize;
}
transform:^UIImage *(UIImage *image, NSURL *url) {
image = [image yy_imageByResizeToSize:CGSizeMake(100, 100) contentMode:UIViewContentModeCenter];
return [image yy_imageByRoundCornerRadius:10];
}
completion:^(UIImage *image, NSURL *url, YYWebImageFromType from, YYWebImageStage stage, NSError *error) {
if (from == YYWebImageFromDiskCache) {
NSLog(@"load from disk cache");
}
}];
5.图片缓存
YYImageCache *cache = [YYWebImageManager sharedManager].cache;
// 获取缓存大小
cache.memoryCache.totalCost;
cache.memoryCache.totalCount;
cache.diskCache.totalCost;
cache.diskCache.totalCount;
// 清空缓存
[cache.memoryCache removeAllObjects];
[cache.diskCache removeAllObjects];
// 清空磁盘缓存,带进度回调
[cache.diskCache removeAllObjectsWithProgressBlock:^(int removedCount, int totalCount) {
// progress
} endBlock:^(BOOL error) {
// end
}];
以上抄自大神郭的GitHub
UIImageView+YYWebImage类
当我们点进方法以后,发现这是一个Category 方法,里面提供了很多方法,单都是基于一个方法扩展的:
- (void)setYy_imageURL:(NSURL *)imageURL {
[self yy_setImageWithURL:imageURL
placeholder:nil
options:kNilOptions
manager:nil
progress:nil
transform:nil
completion:nil];
}
里面可以传图片的url,默认图片,动画效果类型,下载类型,下载管理器,提供的block:进度条回调,完成回调。
这个方法是整个Category的核心,代码比较长,我们分开看。
首先是初始化一个YYWebImageManager,然后动态的添加_YYWebImageSetter属性,为的是管控整个YYImage的下载,查找有没有相同的url在下载,如果有的话就要取消操作,确保同一个url只有一个队列在下载处理:
_YYWebImageSetter *setter = objc_getAssociatedObject(self, &_YYWebImageSetterKey);
if (!setter) {
setter = [_YYWebImageSetter new];
objc_setAssociatedObject(self, &_YYWebImageSetterKey, setter, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
int32_t sentinel = [setter cancelWithNewURL:imageURL];
紧接着YYImage会切到主线程中,做一些配置,设置一下动画,设置一下默认图片,根据刚才的options从不同的地方获取图片:
if ((options & YYWebImageOptionSetImageWithFadeAnimation) &&
!(options & YYWebImageOptionAvoidSetImage)) {
if (!self.highlighted) {
[self.layer removeAnimationForKey:_YYWebImageFadeAnimationKey];
}
}
if (!imageURL) {
if (!(options & YYWebImageOptionIgnorePlaceHolder)) {
self.image = placeholder;
}
return;
}
// get the image from memory as quickly as possible
UIImage *imageFromMemory = nil;
if (manager.cache &&
!(options & YYWebImageOptionUseNSURLCache) &&
!(options & YYWebImageOptionRefreshImageCache)) {
imageFromMemory = [manager.cache getImageForKey:[manager cacheKeyForURL:imageURL] withType:YYImageCacheTypeMemory];
}
if (imageFromMemory) {
if (!(options & YYWebImageOptionAvoidSetImage)) {
self.image = imageFromMemory;
}
if(completion) completion(imageFromMemory, imageURL, YYWebImageFromMemoryCacheFast, YYWebImageStageFinished, nil);
return;
}
if (!(options & YYWebImageOptionIgnorePlaceHolder)) {
self.image = placeholder;
}
这里要注意的是他会在YYImageCacheMemory中寻找一次图片,也就是他默认先在内存中找一下。但是默认的方法中,我们的图片是存在YYImageCacheDisk中的。
所以现在YYImage并没有找到图片,继续往执行,他开出一个异步线程进行下载:
dispatch_async([_YYWebImageSetter setterQueue], ^{
YYWebImageProgressBlock _progress = nil;
if (progress) _progress = ^(NSInteger receivedSize, NSInteger expectedSize) {
dispatch_async(dispatch_get_main_queue(), ^{
progress(receivedSize, expectedSize);
});
};
__block int32_t newSentinel = 0;
__block __weak typeof(setter) weakSetter = nil;
YYWebImageCompletionBlock _completion = ^(UIImage *image, NSURL *url, YYWebImageFromType from, YYWebImageStage stage, NSError *error) {
__strong typeof(_self) self = _self;
BOOL setImage = (stage == YYWebImageStageFinished || stage == YYWebImageStageProgress) && image && !(options & YYWebImageOptionAvoidSetImage);
dispatch_async(dispatch_get_main_queue(), ^{
BOOL sentinelChanged = weakSetter && weakSetter.sentinel != newSentinel;
if (setImage && self && !sentinelChanged) {
BOOL showFade = ((options & YYWebImageOptionSetImageWithFadeAnimation) && !self.highlighted);
if (showFade) {
CATransition *transition = [CATransition animation];
transition.duration = stage == YYWebImageStageFinished ? _YYWebImageFadeTime : _YYWebImageProgressiveFadeTime;
transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
transition.type = kCATransitionFade;
[self.layer addAnimation:transition forKey:_YYWebImageFadeAnimationKey];
}
self.image = image;
}
if (completion) {
if (sentinelChanged) {
completion(nil, url, YYWebImageFromNone, YYWebImageStageCancelled, nil);
} else {
completion(image, url, from, stage, error);
}
}
});
};
newSentinel = [setter setOperationWithSentinel:sentinel url:imageURL options:options manager:manager progress:_progress transform:transform completion:_completion];
weakSetter = setter;
});
核心代码是:
newSentinel = [setter setOperationWithSentinel:sentinel url:imageURL options:options manager:manager progress:_progress transform:transform completion:_completion];
YYWebImageOperation.h类
点进去以后看,发现又是一坨,仔细看会发现,大部分是赋值和一些判断,最关键的创建一个请求去获取图片:
NSOperation *operation = [manager requestImageWithURL:imageURL options:options progress:progress transform:transform completion:completion];
作者对NSOperation进行了自定义,他创建了一个YYWebImageOperation,这是YYImage请求的核心。首先他重写了start方法
- (void)start {
@autoreleasepool {
[_lock lock];
self.started = YES;
if ([self isCancelled]) {
[self performSelector:@selector(_cancelOperation) onThread:[[self class] _networkThread] withObject:nil waitUntilDone:NO modes:@[NSDefaultRunLoopMode]];
self.finished = YES;
} else if ([self isReady] && ![self isFinished] && ![self isExecuting]) {
if (!_request) {
self.finished = YES;
if (_completion) {
NSError *error = [NSError errorWithDomain:NSURLErrorDomain code:NSURLErrorFileDoesNotExist userInfo:@{NSLocalizedDescriptionKey:@"request in nil"}];
_completion(nil, _request.URL, YYWebImageFromNone, YYWebImageStageFinished, error);
}
} else {
self.executing = YES;
[self performSelector:@selector(_startOperation) onThread:[[self class] _networkThread] withObject:nil waitUntilDone:NO modes:@[NSDefaultRunLoopMode]];
if ((_options & YYWebImageOptionAllowBackgroundTask) && _YYSharedApplication()) {
__weak __typeof__ (self) _self = self;
if (_taskID == UIBackgroundTaskInvalid) {
_taskID = [_YYSharedApplication() beginBackgroundTaskWithExpirationHandler:^{
__strong __typeof (_self) self = _self;
if (self) {
[self cancel];
self.finished = YES;
}
}];
}
}
}
}
[_lock unlock];
}
}
这个start方法主要是对队列的一些控制,他会再分出一个网络线程networkThread去做网络请求工作。我们顺着往下看,他进入了:
-(void)_startOperation
这里还没进入请求,YYImage会去查看硬盘内存中的图片,如果有就会执行:
UIImage *image = [self.cache getImageForKey:self.cacheKey withType:YYImageCacheTypeDisk];
如果没有的话,就会去执行_startRequest方法,然后我们就看到了最重要的一段代码:
if (![self isCancelled]) {
_connection = [[NSURLConnection alloc] initWithRequest:_request delegate:[_YYWebImageWeakProxy proxyWithTarget:self]];
if (![_request.URL isFileURL] && (_options & YYWebImageOptionShowNetworkActivity)) {
[YYWebImageManager incrementNetworkActivityCount];
}
}
这里请求还是用的快要淘汰的NSURLConnection,- -让人潸然泪下....接下来就是一些回调了。整个流程结束!
整个流程图如下:
小总结
由此看出YYImage使用非常简单,但内部构造比较复杂。主要的核心模块是:_YYWebImageSetter,YYImageCache,YYWebImageManager,YYWebImageOperation。分工有序,结构清晰,美中不足的是请求方式还是基于快要淘汰的NSURLConnection。不过要修改起来也比较容易,之后我会对YYImage的其他功能做介绍分析,如果你感兴趣可以关注我。
加载Gif动态图
基本使用
YYImage加载gif使用的是YYAnimatedImageView类。我们首先要新建一个YYAnimatedImageView对象:
YYAnimatedImageView *imageView=[YYAnimatedImageView new];
然后后两种加载UIimage的方式:
1.通过URL加载
NSURL *path = [[NSBundle mainBundle]URLForResource:@"guidegif" withExtension:@"gif"]; imageView.yy_imageURL = path;
2.通过YYImage加载
NSURL *path = [[NSBundle mainBundle]URLForResource:@"guidegif_loop" withExtension:@"gif"]; YYImage * image = [YYImage imageWithContentsOfFile:path.path]; imageView.image = image;
YYAnimatedImageView类
他是YYImage加载gif的专供类。他继承于UIImageView,提供了位数不多的几个接口:
@property (nonatomic) BOOL autoPlayAnimatedImage;
@property (nonatomic) NSUInteger currentAnimatedImageIndex;
@property (nonatomic, readonly) BOOL currentIsPlayingAnimation;
@property (nonatomic, copy) NSString *runloopMode;
@property (nonatomic) NSUInteger maxBufferSize;
其中一个还是只读的,并不能设置。这里很不人性化,因为连最起码的loop数量都不开放出来,都写在了.m里面。
我们进入YYAnimatedImageView.m后会发现其实YYAnimatedImageView作为子类重写了很多父类的方法,所以很多设置方法我们要点入进去才能看到。我们顺着运行顺序看下去,首先是对image属性的赋值,这里面最核心的方法是:
- (void)setImage:(id)image withType:(YYAnimatedImageType)type {
[self stopAnimating];
if (_link) [self resetAnimated];
_curFrame = nil;
switch (type) {
case YYAnimatedImageTypeNone: break;
case YYAnimatedImageTypeImage: super.image = image; break;
case YYAnimatedImageTypeHighlightedImage: super.highlightedImage = image; break;
case YYAnimatedImageTypeImages: super.animationImages = image; break;
case YYAnimatedImageTypeHighlightedImages: super.highlightedAnimationImages = image; break;
}
[self imageChanged];
}
所有的对image的设置都会走到这里。主要是暂停动画,然后对image的一个设置,同时进入imageChanged。imageChanged里面主要是一些逻辑处理没什么说的,里面最关键的一句就是:
[self resetAnimated];
resetAnimated是整个实现gif动画的核心,想要高效的展现gif动画就必须重写系统的动画。那这里YYImage的实现方式和FLImage是一样,通过CADisplayLink定时器去绘制gif动画。这样就会使得内存大大的减少,但是CPU的占用会比较大,是以时间换空间的做法:
- (void)resetAnimated {
dispatch_once(&_onceToken, ^{
_lock = dispatch_semaphore_create(1);
_buffer = [NSMutableDictionary new];
_requestQueue = [[NSOperationQueue alloc] init];
_requestQueue.maxConcurrentOperationCount = 1;
_link = [CADisplayLink displayLinkWithTarget:[_YYImageWeakProxy proxyWithTarget:self] selector:@selector(step:)];
if (_runloopMode) {
[_link addToRunLoop:[NSRunLoop mainRunLoop] forMode:_runloopMode];
}
_link.paused = YES;
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didReceiveMemoryWarning:) name:UIApplicationDidReceiveMemoryWarningNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didEnterBackground:) name:UIApplicationDidEnterBackgroundNotification object:nil];
});
[_requestQueue cancelAllOperations];
LOCK(
if (_buffer.count) {
NSMutableDictionary *holder = _buffer;
_buffer = [NSMutableDictionary new];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
// Capture the dictionary to global queue,
// release these images in background to avoid blocking UI thread.
[holder class];
});
}
);
_link.paused = YES;
_time = 0;
if (_curIndex != 0) {
[self willChangeValueForKey:@"currentAnimatedImageIndex"];
_curIndex = 0;
[self didChangeValueForKey:@"currentAnimatedImageIndex"];
}
_curAnimatedImage = nil;
_curFrame = nil;
_curLoop = 0;
_totalLoop = 0;
_totalFrameCount = 1;
_loopEnd = NO;
_bufferMiss = NO;
_incrBufferCount = 0;
}
这里要注意的是,yyimage对播放做了优化,他在显示了一张图片后,立马缓存好下一张为接下来的播放做准备,这就是他比FL更流程的关键,这句代码在他的:
-(void)step:(CADisplayLink *)link
方法中,这个方法是被CADisplayLink绑定了的。
优化的代码:
if (!bufferIsFull && _requestQueue.operationCount == 0) { // if some work not finished, wait for next opportunity
_YYAnimatedImageViewFetchOperation *operation = [_YYAnimatedImageViewFetchOperation new];
operation.view = self;
operation.nextIndex = nextIndex;
operation.curImage = image;
[_requestQueue addOperation:operation];
}
整个流程大致如下:
image.png小总结
YYImage播放gif的能力,是我见过的图片库中最强的。他的流畅和易用值得我们把FL替换掉。美中不足的是他给我们提供的接口太少,我们能完成的功能也就是不停的播放gif。虽然YYImage还提供了一个YYSpriteSheetImage,但是配置比较复杂,而且不能加载gif,只能是图片数组。加载UIImage的时候,推荐用第二种方法--先变成YYImage,因为直接用url可能一开始会找不到图片,造成屏幕闪烁的情况。
YYImageCache
这个类内容比较简单,api也都 通俗易懂,仅仅把注释贴上来即可,深究为什么这么简单,其实还是因为这个类做的事情其实仅仅是统一的调用YYMemoryCache,YYMemoryCache来存取图片而已,具体的存储细节都实现在YYCache里面了,所以这里使用起来才会简单轻松
先看开放了哪些api,都是什么意思
///图片缓存类型
typedef NS_OPTIONS(NSUInteger, YYImageCacheType) {
/// No value.
YYImageCacheTypeNone = 0,
/// Get/store image with memory cache.//从内存中获取
YYImageCacheTypeMemory = 1 << 0,
/// Get/store image with disk cache.//从磁盘中获取
YYImageCacheTypeDisk = 1 << 1,
/// Get/store image with both memory cache and disk cache.//同时获取
YYImageCacheTypeAll = YYImageCacheTypeMemory | YYImageCacheTypeDisk,
};
/**
* YYImageCache是一个用来存储UIImage和image数据的缓存,是基于内存缓存与磁盘缓存实现的
@discussion 磁盘缓存会尝试保护原始的图片数据
如果原始的图片仍是image,会保存为一个png或者jpeg
如果原始图片是一个gif,apng,webp动图,会保存为原始格式
如果原始图片缩放比例不是1,那么缩放值会被保存为一个缩放的数据
虽然图片能被NSCoding协议解码,但是这不是一个最优解:
苹果的确使用UIImagePNGRepresentation()来解码所有类型的图片,但是可能会丢失原始的可变帧数据.结果就是打包成plist文件不能直接查看照片.如果图片没有alpha通道,使用JPEG代理PNG能够保存更多的尺寸和编解码时间.
*/
@interface YYImageCache : NSObject
//缓存名字,默认为nil
@property (copy) NSString *name;
//内存缓存,具体信息看YYMemoryCache
@property (strong, readonly) YYMemoryCache *memoryCache;
//磁盘缓存,具体信息看YYDiskCache
@property (strong, readonly) YYDiskCache *diskCache;
/**
* 当从磁盘缓存请求图片的时候是否解码动图,默认为YES
@discussion 当从磁盘缓存读取图片,会使用YYImage来解码比如WebP/APNG/GIF格式的动图,设置这个值为NO可以忽略动图
*/
@property (assign) BOOL allowAnimatedImage;
/**
* 是否解码图片存储位图,默认为YES
@discussion 如果这个值为YES,图片会通过位图解码来获得更好的用户体验,但是可能会消耗更大的内存资源
*/
@property (assign) BOOL decodeForDisplay;
- (instancetype)init UNAVAILABLE_ATTRIBUTE;
+ (instancetype)new UNAVAILABLE_ATTRIBUTE;
/**
* 单例类初始化方法
*/
+ (instancetype)sharedCache;
/**
* 初始化方法,在多个情况下访问同一个路径会导致缓存不稳定
*
* @param path cache读写的全路径,只初始化一次,你不应该来读写这个路径
*
* @return 一个新的缓存对象,或者返回带nil带error信息
*/
- (instancetype)initWithPath:(NSString *)path NS_DESIGNATED_INITIALIZER;
/**
* 把图片通过一个具体的key存进缓存,同时memory跟disk都会存,这个方法会立刻返回,在后台线程执行
*
* @param image 如果为nil这个方法无效
* @param key 存储图片的key,为nil这个方法无效
*/
- (void)setImage:(UIImage *)image forKey:(NSString *)key;
/**
* 通过一个key把图片缓存,这个方法会立刻返回并在后台执行
如果'type'包括'YYImageCacheTypeMemory',那么图片会被存进memory,如果image为nil会用'imageData'代理
如果'type'包括'YYImageCacheTypeDisk',那么'imageData'会被存进磁盘缓存,如果'imageData'为nil会用image代替
//这里可以看到作者一个思想,如果存进memory,直接存image,会减小很多解码的消耗,如果存disk,会存imageData
*
*/
- (void)setImage:(UIImage *)image imageData:(NSData *)imageData forKey:(NSString *)key withType:(YYImageCacheType)type;
/**
* 通过key移除cache中的一个图片,memory跟disk会同时移除
这个方法会立刻返回并在后台线程执行
*
* @param key 移除图片用的key,为nil的话这个方法没啥用
*/
- (void)removeImageForKey:(NSString *)key;
/**
* 从缓存中通过key删图片
这个方法会立刻返回并在后台线程执行
*
* @param key key
* @param type 从哪删除,跟上个方法不同,这个可以删除指定类型的缓存
*/
- (void)removeImageForKey:(NSString *)key withType:(YYImageCacheType)type;
/**
* 通过key检查缓存中是否有某个图片
如果图片不在内存中,这个方法可能会阻塞线程,知道这个文件读取完毕
*
* @param key key,为nil时返回NO
*
*/
- (BOOL)containsImageForKey:(NSString *)key;
/**
* 跟上个差不多,只不过可以查具体类型的缓存
*/
- (BOOL)containsImageForKey:(NSString *)key withType:(YYImageCacheType)type;
/**
* 通过key获取图片,如果图片不在内存中,这个方法可能会阻塞线程知道文件读取完毕
*
* @param key 一个字符串类型图片缓存key,为nil方法返回nil
*
* @return 通过key查到的图片,没有图片就是nil
*/
- (UIImage *)getImageForKey:(NSString *)key;
/**
* 跟上个方法差不多,只不过从指定缓存类型中获取图片
*/
- (UIImage *)getImageForKey:(NSString *)key withType:(YYImageCacheType)type;
/**
* 通过key异步的获取图片
*
* @param key key
* @param type 缓存类型
* @param block 完成的block回调,主线程调用的
*/
- (void)getImageForKey:(NSString *)key withType:(YYImageCacheType)type withBlock:(void(^)(UIImage *image, YYImageCacheType type))block;
/**
* 通过key查找图片数据data格式,方法会阻塞主线程知道文件读取完毕
*
* @param key key
*
* @return 图片数据,查不到为nil
*/
- (NSData *)getImageDataForKey:(NSString *)key;
/**
* 通过key来异步的获取图片数据
*
* @param key <#key description#>
* @param block 主线程的完成回调
*/
- (void)getImageDataForKey:(NSString *)key withBlock:(void(^)(NSData *imageData))block;
其实现细节如下:
static inline dispatch_queue_t YYImageCacheIOQueue() {
#ifdef YYDispatchQueuePool_h
return YYDispatchQueueGetForQOS(NSQualityOfServiceDefault);
#else
return dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
#endif
}
static inline dispatch_queue_t YYImageCacheDecodeQueue() {
#ifdef YYDispatchQueuePool_h
return YYDispatchQueueGetForQOS(NSQualityOfServiceUtility);
#else
return dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0);
#endif
}
@interface YYImageCache ()
- (NSUInteger)imageCost:(UIImage *)image;
- (UIImage *)imageFromData:(NSData *)data;
@end
@implementation YYImageCache
/**
* 图片消耗
*/
- (NSUInteger)imageCost:(UIImage *)image {
CGImageRef cgImage = image.CGImage;
if (!cgImage) return 1;
CGFloat height = CGImageGetHeight(cgImage);
size_t bytesPerRow = CGImageGetBytesPerRow(cgImage);
NSUInteger cost = bytesPerRow * height;
if (cost == 0) cost = 1;
return cost;
}
/**
* 通过data转换为image
*/
- (UIImage *)imageFromData:(NSData *)data {
NSData *scaleData = [YYDiskCache getExtendedDataFromObject:data];
CGFloat scale = 0;
if (scaleData) {
scale = ((NSNumber *)[NSKeyedUnarchiver unarchiveObjectWithData:scaleData]).doubleValue;
}
if (scale <= 0) scale = [UIScreen mainScreen].scale;
UIImage *image;
if (_allowAnimatedImage) {
image = [[YYImage alloc] initWithData:data scale:scale];
if (_decodeForDisplay) image = [image yy_imageByDecoded];
} else {
YYImageDecoder *decoder = [YYImageDecoder decoderWithData:data scale:scale];
image = [decoder frameAtIndex:0 decodeForDisplay:_decodeForDisplay].image;
}
return image;
}
#pragma mark Public
/**
* 单例类的初始化方法
*/
+ (instancetype)sharedCache {
static YYImageCache *cache = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
NSString *cachePath = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory,
NSUserDomainMask, YES) firstObject];
//拼接路径
cachePath = [cachePath stringByAppendingPathComponent:@"com.ibireme.yykit"];
cachePath = [cachePath stringByAppendingPathComponent:@"images"];
cache = [[self alloc] initWithPath:cachePath];
});
return cache;
}
- (instancetype)init {
@throw [NSException exceptionWithName:@"YYImageCache init error" reason:@"YYImageCache must be initialized with a path. Use 'initWithPath:' instead." userInfo:nil];
return [self initWithPath:nil];
}
/**
* 在初始化的时候同时初始化内存缓存跟磁盘缓存
*
*/
- (instancetype)initWithPath:(NSString *)path {
//在调用父类init之前先初始化一个内存缓存跟磁盘缓存
YYMemoryCache *memoryCache = [YYMemoryCache new];//生成内存缓存
memoryCache.shouldRemoveAllObjectsOnMemoryWarning = YES;//内存警告的时候删除所有内容
memoryCache.shouldRemoveAllObjectsWhenEnteringBackground = YES;//进入后台删除所有内容
memoryCache.countLimit = NSUIntegerMax;//不予限制
memoryCache.costLimit = NSUIntegerMax;//不予限制
memoryCache.ageLimit = 12 * 60 * 60;//cache存在的时间限制设置为12个小时
YYDiskCache *diskCache = [[YYDiskCache alloc] initWithPath:path];//生成磁盘缓存
diskCache.customArchiveBlock = ^(id object) { return (NSData *)object; };//自己来archive数据
diskCache.customUnarchiveBlock = ^(NSData *data) { return (id)data; };//自己unarchive数据
if (!memoryCache || !diskCache) return nil;//如果有任意一个初始化失败,返回nil
self = [super init];
_memoryCache = memoryCache;
_diskCache = diskCache;
_allowAnimatedImage = YES;
_decodeForDisplay = YES;
return self;
}
- (void)setImage:(UIImage *)image forKey:(NSString *)key {
[self setImage:image imageData:nil forKey:key withType:YYImageCacheTypeAll];
}
- (void)setImage:(UIImage *)image imageData:(NSData *)imageData forKey:(NSString *)key withType:(YYImageCacheType)type {
//在每一个方法执行前先检查参数的有效性,非常好的习惯
if (!key || (image == nil && imageData.length == 0)) return;
__weak typeof(self) _self = self;
//如果类型有YYImageCacheTypeMemory
if (type & YYImageCacheTypeMemory) { // add to memory cache
if (image) {
if (image.yy_isDecodedForDisplay) {
//开启了位图解码的话直接把图片丢进内存缓存里面咯
[_memoryCache setObject:image forKey:key withCost:[_self imageCost:image]];
} else {
//否则开启一个异步的解码队列,把图片转成位图,再丢进缓存里面
dispatch_async(YYImageCacheDecodeQueue(), ^{
__strong typeof(_self) self = _self;
if (!self) return;
[self.memoryCache setObject:[image yy_imageByDecoded] forKey:key withCost:[self imageCost:image]];
});
}
} else if (imageData) {//如果图片不存在,图片数据存在,那就通过data生成一个图片,丢进内存中存起来
dispatch_async(YYImageCacheDecodeQueue(), ^{
__strong typeof(_self) self = _self;
if (!self) return;
UIImage *newImage = [self imageFromData:imageData];
[self.memoryCache setObject:[self imageFromData:imageData] forKey:key withCost:[self imageCost:newImage]];
});
}
}
//如果类型包含磁盘缓存,存进磁盘
if (type & YYImageCacheTypeDisk) { // add to disk cache
if (imageData) {
if (image) {
[YYDiskCache setExtendedData:[NSKeyedArchiver archivedDataWithRootObject:@(image.scale)] toObject:imageData];
}
[_diskCache setObject:imageData forKey:key];
} else if (image) {
dispatch_async(YYImageCacheIOQueue(), ^{
__strong typeof(_self) self = _self;
if (!self) return;
NSData *data = [image yy_imageDataRepresentation];
[YYDiskCache setExtendedData:[NSKeyedArchiver archivedDataWithRootObject:@(image.scale)] toObject:data];
[self.diskCache setObject:data forKey:key];
});
}
}
}
/**
* 全删咯
*
*/
- (void)removeImageForKey:(NSString *)key {
[self removeImageForKey:key withType:YYImageCacheTypeAll];
}
//有哪个类型删哪个
- (void)removeImageForKey:(NSString *)key withType:(YYImageCacheType)type {
if (type & YYImageCacheTypeMemory) [_memoryCache removeObjectForKey:key];
if (type & YYImageCacheTypeDisk) [_diskCache removeObjectForKey:key];
}
- (BOOL)containsImageForKey:(NSString *)key {
return [self containsImageForKey:key withType:YYImageCacheTypeAll];
}
- (BOOL)containsImageForKey:(NSString *)key withType:(YYImageCacheType)type {
if (type & YYImageCacheTypeMemory) {
if ([_memoryCache containsObjectForKey:key]) return YES;
}
if (type & YYImageCacheTypeDisk) {
if ([_diskCache containsObjectForKey:key]) return YES;
}
return NO;
}
- (UIImage *)getImageForKey:(NSString *)key {
return [self getImageForKey:key withType:YYImageCacheTypeAll];
}
//通过key找图片,都比较简单
- (UIImage *)getImageForKey:(NSString *)key withType:(YYImageCacheType)type {
if (!key) return nil;
if (type & YYImageCacheTypeMemory) {
UIImage *image = [_memoryCache objectForKey:key];
if (image) return image;
}
if (type & YYImageCacheTypeDisk) {
NSData *data = (id)[_diskCache objectForKey:key];
UIImage *image = [self imageFromData:data];
if (image && (type & YYImageCacheTypeMemory)) {
[_memoryCache setObject:image forKey:key withCost:[self imageCost:image]];
}
return image;
}
return nil;
}
//跟上个方法类似,只不过把查询的结果通过block传递了回去
- (void)getImageForKey:(NSString *)key withType:(YYImageCacheType)type withBlock:(void (^)(UIImage *image, YYImageCacheType type))block {
if (!block) return;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
UIImage *image = nil;
if (type & YYImageCacheTypeMemory) {
image = [_memoryCache objectForKey:key];
if (image) {
dispatch_async(dispatch_get_main_queue(), ^{
block(image, YYImageCacheTypeMemory);
});
return;
}
}
if (type & YYImageCacheTypeDisk) {
NSData *data = (id)[_diskCache objectForKey:key];
image = [self imageFromData:data];
if (image) {
[_memoryCache setObject:image forKey:key];
dispatch_async(dispatch_get_main_queue(), ^{
block(image, YYImageCacheTypeDisk);
});
return;
}
}
dispatch_async(dispatch_get_main_queue(), ^{
block(nil, YYImageCacheTypeNone);
});
});
}
- (NSData *)getImageDataForKey:(NSString *)key {
return (id)[_diskCache objectForKey:key];
}
- (void)getImageDataForKey:(NSString *)key withBlock:(void (^)(NSData *imageData))block {
if (!block) return;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSData *data = (id)[_diskCache objectForKey:key];
dispatch_async(dispatch_get_main_queue(), ^{
block(data);
});
});
}
@end
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