R – UIProgressView not updating while the App loads its resources

uiprogressviewuiview

I am trying to update a UIProgressView progress bar that I have in a UIView during a long resource loading process. Let's say I'm loading a bunch of bitmaps from a NIB file (like maybe a hundred). After I load 10, I issue a .progress to the UIProgressView that is part of a UIView that is already being displayed. So, I issue:

myView.myProgressView.progress=0.2;

Then, I load another 10 bitmaps, and issue:

myView.myProgressView.progress=0.4;

etc., etc. When the app runs, the progress bar doesn't advance. It simply stays at its initial position. At the risk of sounding like a complete moron, do I have to load my resources on a separate thread so the OS can update the UI, or, is there an easier way? Thanks for any assistance.

Best Answer

Yes. Load them on a separate thread. Or just use something like performSelector:

[self performSelector:@selector(setProgressBar) withObject:nil afterDelay:0.0];

(and create a setProgressBar function which reads the current value from a member variable and updates the UI)

Related Solutions

Objective-c – UIProgressView do not update in loop

You are looping through your while loop blocking the main thread, UI elements will not be able to refresh until the main thread becomes available. The best way around this is to run this code in a background thread (making the UI call on the main thread).

Or (I'm not sure about this one, see this discussion) you let the main thread some breathing space by calling

NSDate* futureDate = [NSDate dateWithTimeInterval:0.001 sinceDate:[NSDate date]];
[[NSRunLoop currentRunLoop] runUntilDate:futureDate];

Ios – UIProgressView not updating

Yes the entire purpose of progress view is for threading.

If you're running that loop on the main thread you're blocking the UI. If you block the UI then users can interact and the UI can't update. YOu should do all heavy lifting on the background thread and update the UI on the main Thread.

Heres a little sample

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self performSelectorInBackground:@selector(backgroundProcess) withObject:nil];

}

- (void)backgroundProcess
{    
    for (int i = 0; i < 500; i++) {
        // Do Work...

        // Update UI
        [self performSelectorOnMainThread:@selector(setLoaderProgress:) withObject:[NSNumber numberWithFloat:i/500.0] waitUntilDone:NO];
    }
}

- (void)setLoaderProgress:(NSNumber *)number
{
    [progressView setProgress:number.floatValue animated:YES];
}

Best Answer

Related Solutions

Objective-c – UIProgressView do not update in loop

Ios – UIProgressView not updating

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