Playing an animation while data is loading - ios

Question

Currently in my AppDelegate.m I have the code:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
[self.window makeKeyAndVisible];
CGRect rect = [[UIScreen mainScreen] bounds];
UIImageView *imageView =[[UIImageView alloc] initWithFrame:rect];
imageView.animationImages = [NSArray arrayWithObjects:
[UIImage imageNamed:#"Comp 2_00000.png"],..., nil];
imageView.animationDuration = 6;
imageView.animationRepeatCount = 1;
[imageView startAnimating];
[self.window addSubview:imageView];
return YES;
}
Which plays an animation I have once my view did load code in my ViewController.m has loaded some data which takes around 5 seconds.
I load the data like this using JSON and URLS:
NSURL *url = [NSURL URLWithString:#"http://xxxxxxxx.co.uk/untitled%20folder/jsonimages.php"];
NSData *jsonData = [NSData dataWithContentsOfURL:url];
NSError *error = nil;
NSDictionary *result = [NSJSONSerialization JSONObjectWithData:jsonData
options:NSJSONReadingMutableContainers error:&error];
Is there anyway for the animation to play while the data is loading?

Answer 1

Create a helper function (make it static if you need to reuse it):
Function:
-(UIImageView *) InitImageView{
[self.window makeKeyAndVisible];
CGRect rect = [[UIScreen mainScreen] bounds];
UIImageView *imageView =[[UIImageView alloc] initWithFrame:rect];
imageView.animationImages = [NSArray arrayWithObjects:
[UIImage imageNamed:#"Comp 2_00000.png"],..., nil];
//imageView.animationDuration = 6;
imageView.animationRepeatCount = 1;
[self.view addSubview:imageView];
return imageView;
}
Ansynchronous Task:
//Start Animation
UIImageView *imageView = [self InitImageView];
[imageView startAnimating];
dispatch_queue_t queue = dispatch_queue_create("co.uk.bits.bots", NULL);
dispatch_async(queue, ^{
NSURL *url = [NSURL URLWithString:#"http://xx.co.uk/jsonimages.php"];
NSData *jsonData = [NSData dataWithContentsOfURL:url];
NSError *error = nil;
NSDictionary *result = [NSJSONSerialization JSONObjectWithData:jsonData
options:NSJSONReadingMutableContainers error:&error];
dispatch_async(dispatch_get_main_queue(), ^{
//Stop Animation
[imageView stopAnimating];
});
});

Answer 2

What you could do is to dispatch the data request and then call the animation:
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSURL *url = [NSURL URLWithString:#"http://xxxxxxxx.co.uk/untitled%20folder/jsonimages.php"];
NSData *jsonData = [NSData dataWithContentsOfURL:url];
NSError *error = nil;
NSDictionary *result = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers error:&error];
dispatch_async(dispatch_get_main_queue(), ^{
//Main thread stuff, after loading the data
[self animate];
});
});
....
- (void)animate {
CGRect rect = [[UIScreen mainScreen] bounds];
UIImageView *imageView =[[UIImageView alloc] initWithFrame:rect];
imageView.animationImages = [NSArray arrayWithObjects:
[UIImage imageNamed:#"Comp 2_00000.png"],..., nil];
imageView.animationDuration = 6;
imageView.animationRepeatCount = 1;
[imageView startAnimating];
[self.view addSubview:imageView];
}

Answer 3

This code may get your app rejected from the app store because it will force the user to wait for six seconds on every app launch. the Apple guidelines say that app launches should happen as fast as possible.
Could you refactor it so that your initial view controller can be displayed without the data at first, then update it incrementally as the data becomes available?
If the data is loaded from the network you could also cache it so that subsequent launches are faster.