my problem is this:
I want to show ProgressView for files downloading.For some reason the ProgressView gradually rises, showing how much file is already downloaded , and just immediately fills up when files are still not downloaded! What do I need to fix or how to implement it?
Here is my source code:
- (IBAction)download:(id)sender { // Determile cache file path NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); progressSlider.progress = 0.0; for (i=0;i<=7;i++) { //Updating progressView and progressLabel progressLabel.text = [NSString stringWithFormat:@"Загружено: %d из 7",i]; progressView.progress = (float)i/(float)7; NSString *filePath = [NSString stringWithFormat:@"%@/avto-0-%d.html", [paths objectAtIndex:0],i]; // Download and write to file NSString *mustUrl = [NSString stringWithFormat:@"http://www.mosgortrans.org/pass3/shedule.php?type=avto&%@", [listOfAvtoUrl objectAtIndex:i]]; NSURL *url = [NSURL URLWithString:mustUrl]; NSData *urlData = [NSData dataWithContentsOfURL:url]; [urlData writeToFile:filePath atomically:YES]; } }
I think that it is related to threads and how the main thread will refresh the view.
Two cases can occur:
You are on the main thread when calling this method
In such case, you do not allow the main thread to execute refresh routines. Move all this download to a background queue using GCD, and call back the main thread like explained in pt.2.
To put everything in a background queue, you could call:
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^ { // your download code goes here });
Or, You are already on the background thread, then use the following lines to call back to the main thread:
dispatch_async(dispatch_get_main_queue(), ^ { progressView.progress = (float)i/(float)7; });
Final answer:
- (IBAction)download:(id)sender { dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^ { // Determile cache file path NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); progressSlider.progress = 0.0; for (i=0;i<=7;i++) { //Updating progressView and progressLabel progressLabel.text = [NSString stringWithFormat:@"Загружено: %d из 7",i]; dispatch_async(dispatch_get_main_queue(), ^ { progressView.progress = (float)i/(float)7; }); NSString *filePath = [NSString stringWithFormat:@"%@/avto-0-%d.html", [paths objectAtIndex:0],i]; // Download and write to file NSString *mustUrl = [NSString stringWithFormat:@"http://www.mosgortrans.org/pass3/shedule.php?type=avto&%@", [listOfAvtoUrl objectAtIndex:i]]; NSURL *url = [NSURL URLWithString:mustUrl]; NSData *urlData = [NSData dataWithContentsOfURL:url]; [urlData writeToFile:filePath atomically:YES]; } }); }
