怎么在加载图片时得到它的加载进度

最新推荐文章于 2023-09-26 01:56:07 发布

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本文介绍了一种在iOS应用中使用NSURLConnection从指定URL下载图片的方法。通过实现NSURLConnectionDelegate，可以监控下载进度并记录文件总大小。下载完成后，数据将转换为UIImage格式。

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- (void)viewDidLoad

{

   [super viewDidLoad];

    

    NSURL* leUrl = [NSURL URLWithString:@"http://bizhi.zhuoku.com/2013/02/19/KTM_350_Freeride/Ktm_350_freeride_06.jpg"];

    NSURLRequest* leRequest = [NSURLRequest requestWithURL:leUrl];

    [[[NSURLConnection alloc] initWithRequest:leRequest delegate:self] autorelease];



}



#pragma mark - NSURLConnectionDataDelegate

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response

{

    NSHTTPURLResponse* httpResponse = (NSHTTPURLResponse*)response;

    if(httpResponse && [httpResponse respondsToSelector:@selector(allHeaderFields)]){

        

        NSDictionary *httpResponseHeaderFields = [httpResponse allHeaderFields];



        _totalSize = [[httpResponseHeaderFields objectForKey:@"Content-Length"] longLongValue];

        NSLog(@"total = %lld", _totalSize);

    }

    

    if(_returnData == nil){

        _returnData = [[NSMutableData alloc] init];

    }

    

}



- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data

{

    [_returnData appendData:data];

    long long int hasFinished = [_returnData length];

    NSLog(@"总共%lld 已下载%lld 进度%f", _totalSize, hasFinished, hasFinished*1.0/_totalSize);

}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection

{

    // NSData -> UIImage

    

    [connection cancel];

}