下載圖片時的進度條

Question

如何添加進度條來下載大圖或任何文件？這裏是我的代碼：

NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, 
                  NSUserDomainMask, YES); 

     NSString *docsPath = [paths objectAtIndex:0]; 
     NSString *downloadPath = [[[NSString alloc]initWithFormat:@"http://www.zzz.com/%@.jpg",chartFileName]autorelease]; 
     NSString *savePath = [[[NSString alloc]initWithFormat:@"%@/%@.jpg",docsPath, chartFileName]autorelease]; 
     NSURL *url = [[NSURL alloc]initWithString:downloadPath]; 
     NSData *downloadedChartData = [NSData dataWithContentsOfURL:url]; 
     [url release]; 
     [downloadedChartData writeToFile:savePath atomically:YES]; 

Answer 1

你可以覆蓋連接：didReceiveData：在你的NSURLConnection調用中。請參閱此處瞭解更多：

How to integrate NSURLConnection with UIProgressView?

Answer 2

在後臺運行一個選擇器，檢查圖像的下載大小，並將其與所需大小進行比較。然後將進度條的％設置爲已下載/需要。