AFNetworking下载网络相关的附件（音视频）等到本地app包中做离线来提高用户体验

使用场景:

有时我们做的app在请求网络相关的附件资源时有图片的也有音视频的，请求图片我们常用的第三方库一般是

SDWebImage就足够了，但SDWebImage不支持对像音频、视频及压缩zip等附件的下载支持，这时我们可以利用

AFNetworking的AFHTTPRequestOperation类来完成下载并保存到指定的app的Caches目录下，底层对这块的封装

代码如下:

.h头文件接口

[objc] view
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/**

* 下载文件

*

* @param string aUrl 请求文件地址

* @param string aSavePath 保存地址

* @param string aFileName 文件名

* @param int aTag tag标识

*/

- (void)downloadFileURL:(NSString *)aUrl savePath:(NSString *)aSavePath fileName:(NSString *)aFileName tag:(NSInteger)aTag;

.m实现代码如下:

[objc] view
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/**

* 下载文件

*/

- (void)downloadFileURL:(NSString *)aUrl savePath:(NSString *)aSavePath fileName:(NSString *)aFileName tag:(NSInteger)aTag

{

NSFileManager *fileManager = [NSFileManager defaultManager];

//检查本地文件是否已存在

NSString *fileName = [NSString stringWithFormat:@"%@/%@", aSavePath, aFileName];

//检查附件是否存在

if ([fileManager fileExistsAtPath:fileName]) {

NSData *audioData = [NSData dataWithContentsOfFile:fileName];

[self requestFinished:[NSDictionary dictionaryWithObject:audioData forKey:@"res"] tag:aTag];

}else{

//创建附件存储目录

if (![fileManager fileExistsAtPath:aSavePath]) {

[fileManager createDirectoryAtPath:aSavePath withIntermediateDirectories:YES attributes:nil error:nil];

}

//下载附件

NSURL *url = [[NSURL alloc] initWithString:aUrl];

NSURLRequest *request = [NSURLRequest requestWithURL:url];

AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];

operation.inputStream = [NSInputStream inputStreamWithURL:url];

operation.outputStream = [NSOutputStream outputStreamToFileAtPath:fileName append:NO];

//下载进度控制

/*

[operation setDownloadProgressBlock:^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead) {

NSLog(@"is download：%f", (float)totalBytesRead/totalBytesExpectedToRead);

}];

*/

//已完成下载

[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {

NSData *audioData = [NSData dataWithContentsOfFile:fileName];

//设置下载数据到res字典对象中并用代理返回下载数据NSData

[self requestFinished:[NSDictionary dictionaryWithObject:audioData forKey:@"res"] tag:aTag];

} failure:^(AFHTTPRequestOperation *operation, NSError *error) {

//下载失败

[self requestFailed:aTag];

}];

[operation start];

}

}