如何在從服務器下載文件時創建進度條

Question

如何在從iPhone中的服務器下載文件時創建進度條。

Answer 1

使用download helper class下載一個文件，並將其顯示進度條指示太..

Answer 2

以下爲下載進度條顯示

進口「UIDownloadBar.h」

@interface yourClassViewCtr : UIViewController <uidownloadbardelegate ,UIAlertViewDelegate> { 
    UIDownloadBar *bar; 
    UILabel *lblForDisplay; 
    UIAlertView *alert; 
} 

代表法碼代碼

#pragma mark - UIDownloadBar Delegate Methods 

- (void)downloadBar:(UIDownloadBar *)downloadBar didFinishWithData:(NSData *)fileData suggestedFilename:(NSString *)filename { 
// NSLog(@"%@", filename); 
// NSLog(@"%@",fileData); 

    UIImage *img=[UIImage imageWithData:fileData]; 
    UIImageView *imgVctr=[[UIImageView alloc]initWithFrame:CGRectMake(40, 25, 200, 100)]; 
    imgVctr.image=img; 

    //store locally data into the resource folder. 
    [self.view addSubview:imgVctr]; 
    [alert dismissWithClickedButtonIndex:0 animated:YES]; 
} 

- (void)downloadBar:(UIDownloadBar *)downloadBar didFailWithError:(NSError *)error { 
    NSLog(@"%@", error); 
} 

- (void)downloadBarUpdated:(UIDownloadBar *)downloadBar { 
} 

For more detail visit following tutorial.

這可能對你有幫助。

Answer 3

你的UI的主線程中不應該有進度條。

最佳方法是創建另一個線程並將您的進度欄放在那裏。您可以發送此線程一些更新信息，如百分比，以便更新您喜歡的速度。

一旦你完成下載的線程可以被殺死 - 或留下來在後臺下載。

Answer 4

- (id)initWithFrame:(CGRect)frame 
{ 
self = [super initWithFrame:frame]; 
if (self) { 

    [self setBackgroundColor:[UIColor colorWithWhite:0 alpha:0.8]]; 
    [self setAutoresizesSubviews:YES]; 

    self.downloadMessage=[[[UILabel alloc] initWithFrame:CGRectMake(40, 0, frame.size.width-80, frame.size.height/2)] autorelease]; 

    [self.downloadMessage setTextAlignment:UITextAlignmentCenter]; 
    [self.downloadMessage setFont:[UIFont boldSystemFontOfSize:11]]; 
    [self.downloadMessage setAutoresizingMask:UIViewAutoresizingFlexibleRightMargin|UIViewAutoresizingFlexibleLeftMargin]; 
    [self.downloadMessage setText:@"Downloading Assets..."]; 
    [self.downloadMessage setBackgroundColor:[UIColor clearColor]]; 
    [self addSubview:self.downloadMessage]; 
    [self.downloadMessage setTextColor:[UIColor whiteColor]]; 

    float offset=(frame.size.width-200)/2; 
    self.progressiveView=[[[UIProgressView alloc] initWithProgressViewStyle:UIProgressViewStyleDefault] autorelease]; 

    [self.progressiveView setFrame:CGRectMake(offset, frame.size.height/2, 200, frame.size.height/2)]; 
    [self.progressiveView setAutoresizingMask:UIViewAutoresizingFlexibleRightMargin|UIViewAutoresizingFlexibleLeftMargin]; 
    [self addSubview:self.progressiveView]; 
} 
return self; 
} 

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

expectedLength+=response.expectedContentLength; 
} 
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{ 

@try{ 

int index=[self.urlConnections indexOfObject:connection]; 
progressValue+=((float)((float)data.length/(float)expectedLength))*0.9; 
[self.progressiveView setProgress:progressValue]; 
[[self.preCacheDatas objectAtIndex:index] appendData:data]; 
} 
@catch (NSException *exception){ 
} 
}