iOS之GIF动画文件的播放

前言

播放gif动画的方法有多种：
1、将gif图片分解成多张图片使用UIImageView播放
2、webView直接播放.gif文件
3、使用第三方播放

一、UIImageView实现gif动画

用imageView制作gif动画最经典就是汤姆猫，感兴趣的可以百度或者谷歌一下“iOS汤姆猫源代码”。在这里只是简单的介绍imageview的gif动画实现，你也可以用计时器（NSTimer）.在做这些之前必须要将gif分解成一张张PNG图片。

UIImageView *gifImageView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, 100, 100)];    gifImageView.center = self.view.center;    [self.view addSubview:gifImageView];    NSMutableArray *images = [NSMutableArray array];    for (int i=0; i < 10; i++) {        [images addObject:[UIImage imageNamed:[NSString stringWithFormat:@"image%d",i]]];    }    gifImageView.animationImages = images;    gifImageView.animationDuration = 5.0;    gifImageView.animationRepeatCount = NSUIntegerMax;    [gifImageView startAnimating];

二、UIWebView实现.gif动画文件的播放
webView可以加载很多文件是个很强大的控件，实现gif播放简单直接不过只能循环播放。

CGSize size = [UIImage imageNamed:@"name.gif"].size;    UIWebView *webView = [[UIWebView alloc]initWithFrame:CGRectMake(0, 0, size.width, size.height)];    webView.center = self.view.center;    webView.userInteractionEnabled = NO;    webView.backgroundColor = [UIColor whiteColor];    [self.view addSubview:webView];    NSData *data = [NSData dataWithContentsOfFile:[[NSBundle mainBundle]pathForResource:@"name" ofType:@"gif"]];    [webView loadData:data MIMEType:@"image/gif" textEncodingName:nil baseURL:nil];

三、第三方实现播放gif动画
首先需要导入两个库：ImageIO.framework和MobileCoreServices.framework;具体实现是采用ImageIO库对.gif文件进行解析获取相关资源最后进行动画的播放，下面是自己写的播放gif动画的loading实例

1、GifLoadingView.h

#import <UIKit/UIKit.h>@interface GifLoadingView : UIView+(void)startLoading;+(void)endLoading;@end

2、GifLoadingView.m

#define  GIF_WIDTH 80*1.2#import "GifLoadingView.h"#import <ImageIO/ImageIO.h>#import <MobileCoreServices/MobileCoreServices.h>@interface GifLoadingView()@property (nonatomic, strong)NSMutableArray<UIImage *> *images;@property (nonatomic, strong)GifLoadingView *loading;@property (nonatomic, strong)UIView *gifContentView;@property (nonatomic, assign)CGImageSourceRef gif;@property (nonatomic, strong)NSDictionary *gifDic;@property (nonatomic, assign)size_t index;@property (nonatomic, assign)size_t count;@property (nonatomic, strong)NSTimer *timer;@end@implementation GifLoadingView- (instancetype)init{    self = [self initWithFrame:CGRectMake(0, 0, GIF_WIDTH, GIF_WIDTH)];    if (self) {        self.backgroundColor = [UIColor whiteColor];        self.layer.cornerRadius = GIF_WIDTH/2;        self.layer.masksToBounds = YES;        [self createGif];    }    return self;}- (void)createGif{//    _gifContentView.layer.borderColor = UIColorFromRGB(No_Choose_Color).CGColor;//    _gifContentView.layer.borderWidth = 1.0;    NSDictionary *gifLoopCount = [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:0] forKey:(NSString *)kCGImagePropertyGIFLoopCount];    _gifDic = [NSDictionary dictionaryWithObject:gifLoopCount forKey:(NSString *)kCGImagePropertyGIFDictionary];    NSData *gif = [NSData dataWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"loading" ofType:@"gif"]];    _gif = CGImageSourceCreateWithData((CFDataRef)gif, (CFDictionaryRef)_gifDic);    _count = CGImageSourceGetCount(_gif);    _timer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(startLoading) userInfo:nil repeats:YES];    [_timer fire];}-(void)startLoading{    _index ++;    _index = _index%_count;    CGImageRef ref = CGImageSourceCreateImageAtIndex(_gif, _index, (CFDictionaryRef)_gifDic);    self.layer.contents = (__bridge id)ref;    CFRelease(ref);}+ (void)startLoading{    GifLoadingView *loading = [[GifLoadingView alloc]init];    UIWindow *keyView = [UIApplication sharedApplication].keyWindow;    loading.center = keyView.center;    [keyView addSubview:loading];    dispatch_main_after(5.0f, ^{        [GifLoadingView endLoading];    });}+ (void)endLoading{    for (UIView *view in [UIApplication sharedApplication].keyWindow.subviews) {        if ([view isKindOfClass:[GifLoadingView class]]) {//            [UIView animateWithDuration:1.0 animations:^{//                view.alpha = 0;//            } completion:^(BOOL finished) {               [((GifLoadingView *)view) stopGif];               [view removeFromSuperview];//            }];        }    }}- (void)stopGif{    [_timer invalidate];    _timer = nil;}- (void)dealloc{    CFRelease(_gif);}static void dispatch_main_after(NSTimeInterval delay, void (^block)(void)){    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delay * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{        block();    });}

总结
简要总结一些三个方法的利弊：

UIImageView采用帧动画将图片一张张显示，这个方法可以调节播放次数和速度但图片过多过大内存会很有压力。另外在保证播放的动画清晰和时长的情况下.gif文件大小会远小于多张.png图片的大小。

UIWebView实现播放gif特别简单直接，如果你只想单纯的播放一下建议使用此方法。弊端就是只能循环播放(>_<)，无法控制它的暂停和其他操作。

使用第三方播放gif动画集合了第一种方法好处你可以对动画进行一系列操作，在.gif文件比较大的情况下建议使用。（个人喜欢使用此方法）。