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我正面臨一個問題，使得3個文件的異步下載隊列。IOS隊列異步下載
當我完成下載和保存的第一文件開始下載第二個，然後第三個我想......
對於我使用3 IBAction爲下載到的文件夾，它的工作時刻完美，但爲了使所有文件自動無效。
實現此文件下載隊列的最佳方式是什麼？ 我知道我必須有關於didReceiveData的聲明，但我需要幫助才能使其工作。
這是我使用的代碼：
// Download song 1
- (IBAction)download {
[self performSelector:@selector(downloadmusic) withObject:nil afterDelay:0.0];
}
- (void)downloadmusic
{
self.log = [NSMutableString string];
[self doLog:@"1/13"];
// Retrieve the URL string
int which = [(UISegmentedControl *)self.navigationItem.titleView selectedSegmentIndex];
NSArray *urlArray = [NSArray arrayWithObjects: SONG1_URL, nil];
NSString *urlString = [urlArray objectAtIndex:which];
// Prepare for download
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
// Set up the Download Helper and start download
[DownloadHelper sharedInstance].delegate = self;
[DownloadHelper download:urlString];
}
// Download song 2
- (void)downloadmusic2
{
self.log = [NSMutableString string];
[self doLog:@"2/13"];
// Retrieve the URL string
int which = [(UISegmentedControl *)self.navigationItem.titleView selectedSegmentIndex];
NSArray *urlArray = [NSArray arrayWithObjects: SONG2_URL, nil];
NSString *urlString = [urlArray objectAtIndex:which];
// Prepare for download
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
// Set up the Download Helper and start download
[DownloadHelper sharedInstance].delegate = self;
[DownloadHelper download:urlString];
}
// Download song 3
- (void)downloadmusic3
{
self.log = [NSMutableString string];
[self doLog:@"3/13"];
// Retrieve the URL string
int which = [(UISegmentedControl *)self.navigationItem.titleView selectedSegmentIndex];
NSArray *urlArray = [NSArray arrayWithObjects: SONG3_URL, nil];
NSString *urlString = [urlArray objectAtIndex:which];
// Prepare for download
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
// Set up the Download Helper and start download
[DownloadHelper sharedInstance].delegate = self;
[DownloadHelper download:urlString];
}
- (void) doLog: (NSString *) formatstring, ...
{
va_list arglist;
if (!formatstring) return;
va_start(arglist, formatstring);
NSString *outstring = [[[NSString alloc] initWithFormat:formatstring arguments:arglist] autorelease];
va_end(arglist);
[self.log appendString:outstring];
[self.log appendString:@"\n"];
[textView setText:self.log];
}
- (void) restoreGUI
{
self.navigationItem.rightBarButtonItem = BARBUTTON(@"Get Data", @selector(action:));
if ([[NSFileManager defaultManager] fileExistsAtPath:DEST_PATH])
self.navigationItem.leftBarButtonItem = BARBUTTON(@"Play", @selector(startPlayback:));
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];
[(UISegmentedControl *)self.navigationItem.titleView setEnabled:YES];
[progress setHidden:YES];
}
- (void) dataDownloadAtPercent: (NSNumber *) aPercent
{
[progress setHidden:NO];
[progress setProgress:[aPercent floatValue]];
}
- (void) dataDownloadFailed: (NSString *) reason
{
[self restoreGUI];
if (reason) [self doLog:@"Download failed: %@", reason];
}
- (void) didReceiveFilename: (NSString *) aName
{
self.savePath = [DEST_PATH stringByAppendingString:aName];
}
- (void) didReceiveData: (NSData *) theData
{
if (![theData writeToFile:self.savePath atomically:YES])
[self doLog:@"Error writing data to file"];
[theData release];
[self restoreGUI];
[self doLog:@"Download succeeded"];
//[self performSelector:@selector(downloadmusic2) withObject:nil afterDelay:1.0];
//[self performSelector:@selector(downloadmusic3) withObject:nil afterDelay:1.0];
}