iOS move database update off the main thread - insert a splash view - ios

Question

I'm new to objective-c so please bear with this long explanation, I hope it will help other beginners. I have been successfully making some changes to an existing iPad app. However, the original install/update routine has hit the failed to launch in time barrier. The posts here have helped me greatly to understand the problem and which direction(s) to research.
I have compiled a solution from different posts here and elsewhere as I did not find a global line-by-line for beginners solution.
I understand that I need to pull the database init/update out of didFinishLaunchingWithOptions and return from here asap with an instantiated UIViewController that will do the DB stuff off the main thread (thanks to all the posters on the subject).
NOTE that the rootVC that is usually called here cannot init if the data is not ready and intact. So just going async on the DB routine doesn't help me because the rootVC gets there first and bombs out when it doesn't find the data it requires.
i.e. I need to delay the rootVC while we do anything we need to do and in peace. I choose to load the UILaunchImage to be seamless and add a spinner.
The question is:
1) Have I done it correctly so that I will never get bitten and 8badf00d again and especially without adding other side effects? Or should I have done it otherwise, maybe in a wrapper init method of the existing rootVC?
2) What about the dealloc, rootViewController or splashViewController? I would think that it is rather rootViewController by this stage. Confused.
3) It works but is this really replacing (and removing) splashViewController by rootViewController as the rootVC? Or am I piling them up...
BEFORE
RAppDelegate.h
#import <UIKit/UIKit.h>
#import "RDataManager.h"
#import "RRootViewController.h"
#import "RScreenViewController.h"
#interface RAppDelegate : NSObject <UIApplicationDelegate>
{
UIWindow *window;
RRootViewController *rootViewController;
}
#property (nonatomic, retain) IBOutlet UIWindow *window;
#property (nonatomic, readonly) RRootViewController *rootViewController;
#end
RAppDelegate.m
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
[[RDataManager sharedManager] updateDatabase]; // This is what takes time...
rootViewController = [[RRootViewController alloc] initAtScreen:kScreenTypeIndex withCar:carId];
rootViewController.wantsFullScreenLayout = YES;
self.window.rootViewController = rootViewController;
[self.window makeKeyAndVisible];
return YES;
}
...
- (void)dealloc
{
[rootViewController.view removeFromSuperview];
[rootViewController release];
[window release];
[super dealloc];
}
AFTER
RAppDelegate.h
#import <UIKit/UIKit.h>
#import "RDataManager.h"
#import "RScreenViewController.h"
#import "RSplashViewController.h"
#interface RAppDelegate : NSObject <UIApplicationDelegate>
{
UIWindow *window;
RSplashViewController *splashViewController;
}
#property (nonatomic, retain) IBOutlet UIWindow *window;
#property (nonatomic, readonly) RSplashViewController *splashViewController;
#end
RAppDelegate.m
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
splashViewController = [[RSplashViewController alloc] init];
splashViewController.wantsFullScreenLayout = YES;
self.window.rootViewController = splashViewController;
[self.window makeKeyAndVisible];
return YES;
}
...
- (void)dealloc
{
[splashViewController.view removeFromSuperview];
[splashViewController release];
[window release];
[super dealloc];
}
RSplashViewController.h
#import <UIKit/UIKit.h>
#import "RRootViewController.h"
#interface RSplashViewController : UIViewController
{
UIImageView *splashImageView;
RRootViewController *rootViewController;
UIActivityIndicatorView *spinner;
}
#property (nonatomic, retain) UIImageView *splashImageView;
#property (nonatomic, readonly) RRootViewController *rootViewController;
#end
RSplashViewController.m
#import "RSplashViewController.h"
#import "RDataManager.h"
#interface RSplashViewController ()
#end
#implementation RSplashViewController
#synthesize splashImageView;
#synthesize rootViewController;
- (void) loadView
{
CGRect appFrame = [UIInterface frame];
UIView *view = [[UIView alloc] initWithFrame:appFrame];
self.view = view;
[view release];
NSString *splashFile = [[NSBundle mainBundle] pathForResource:#"LaunchImage-jaguar-Landscape~ipad" ofType:#"png"];
UIImage *splashImage = [[UIImage alloc] initWithContentsOfFile:splashFile];
splashImageView = [[UIImageView alloc] initWithImage:splashImage];
[self.view addSubview:splashImageView];
[splashImage release];
spinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
CGRect frame = spinner.frame;
frame.origin.x = CGRectGetMidX(self.view.frame) - CGRectGetWidth(spinner.frame) / 2;
frame.origin.y = 650;
spinner.frame = frame;
spinner.hidesWhenStopped = YES;
[self.view addSubview:spinner];
[spinner startAnimating];
}
- (void) viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
// how we stop DB refresh from freezing the main UI thread
dispatch_queue_t updateQueue = dispatch_queue_create("updateDB", NULL);
dispatch_async(updateQueue, ^{
// do our long running process here
[[RDataManager sharedManager] updateDatabase];
// do any UI stuff on the main UI thread
dispatch_async(dispatch_get_main_queue(), ^{
[spinner stopAnimating];
[splashImageView removeFromSuperview];
rootViewController = [[RRootViewController alloc] initAtScreen:kScreenTypeGarage withCar:nil needSplashScreen:YES];
[self.view addSubview:rootViewController.view];
});
});
dispatch_release(updateQueue);
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (void) dealloc
{
[super dealloc];
}
#end

Answer 1

To answer my questions.
1) Yes this is safe, either with SplashViewController or rootVC init wrapper. Ran it as ad-hoc for 2 minutes no problems. Double checked that the update was indeed running in a separate thread (Xcode debug window pane).
2) Non issue since I moved to a rootVC init wrapper solution and reverted to dealloc'ing rootViewController.
3) Problem solved by 2).
I also managed to reduce the update time by 90% which is the ideal solution anyway, but good to know that I am also safely out of the way of the watchdog timer.