Question

I am new to Objective C and IOS programming so please be patient with me.

I am getting a JSON string from my server which I am using to add images or buttons to my view my view is a UIScrollView,

The below code works great and does exactly what I want but I only see all the buttons once the loop is completed which takes some time.

What I was expecting is to see each button being added to the view one by one. Is there a better way to implement this and or is this the expected behavior for this as I described.

Thank You

for (NSDictionary *num in jsonOBJ) {

        fullURL = [urlWithOut stringByAppendingString:[num objectForKey:@"src"]];

        img = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL: [NSURL URLWithString:fullURL]]];
        button = [UIButton buttonWithType:UIButtonTypeCustom];
        button.frame = CGRectMake(3+i*h, 3+i*w,76, 76);
        button.layer.borderWidth = 1.0;
        button.layer.borderColor = [UIColor redColor].CGColor;

        [button addTarget:self action:@selector(push:) forControlEvents:UIControlEventTouchUpInside];

        [self.scroll addSubview:button];

        [button setImage:img forState:UIControlStateNormal];
        [img release];

        NSString *string = @"";
        NSString *realstring = [string stringByAppendingString: [num objectForKey:@"id"]];

        button.tag = [realstring intValue];

        self.scroll.contentSize = CGSizeMake(320,total);
    }

Answer 1

You need to run image loading process in background thread, that should solve it. I’ll explain – image loading stops the UI while loop actually is still running, adding buttons with images, but they won’t display until all images are loaded.