Intercepting initial ViewController on applicationDidBecomeActive, before anything appears - ios

Question

I'd like to display a custom View Controller immediately each time the user returns to the app. Currently I can do this easily with didFinishLaunchingWithOptions by simply choosing what the initial rootViewController will be before anything appears on the screen.
However if I put the intercept VC in applicationDidBecomeActive, then the previous VC is on screen for half a second, before I can load the intercept.
How can I make it so when the app is put back into foreground the VC immediately on screen is my custom intercept? That VC will then restore the foreground view on its own.
FYI: I am using this intercept to verify the user is within supported location, then allowing the app to return to state or display an unsupported screen.

Answer 1

There are two solutions to this problem.
Solution:1 You could write your interceptVC - functionality on the application's delegate method
func applicationWillEnterForeground(application: UIApplication)
instead of writing in
func applicationDidBecomeActive(application: UIApplication)
Solution:2
As you did the interceptVC - functionary on applicationDidBecomeActive can also be applied to while application went background,
func applicationDidEnterBackground(application: UIApplication)
so that, when the applicationDidBecomActive delay can be covered.
Note: Here the application once entered background will always has the interceptVC in the background.

Answer 2

Solution by OP.
A solution I used was to set a custom background image when the app resigns active. This is also the screen shown in the multitask selector. When the app resumes active it is the initial screen shown until my interceptVC loads. The image I used is the same background as my interceptVC so it appears instant. This was also easier than attempting to preload the intercept VC on resign of active. Some fade animations are also used on the imageview to make it smoother and non-jarring.
- (void)applicationWillResignActive:(UIApplication *)application {
// fill screen with our own imageView
UIImageView *imageView = [[UIImageView alloc] initWithFrame:self.window.frame];
if(IS_IPHONE_6P){
imageView.image = [UIImage imageNamed:#"splash_1242x2208.png"];
} else if(IS_IPHONE_6){
imageView.image = [UIImage imageNamed:#"splash_750x1334.png"];
} else if(IS_IPHONE_5){
imageView.image = [UIImage imageNamed:#"splash_640x1136.png"];
} else if(IS_IPHONE_4_OR_LESS){
imageView.image = [UIImage imageNamed:#"splash_640x960.png"];
} else {
// should not happen
imageView.image = [UIImage imageNamed:#"splash_750x1334.png"];
}
imageView.tag = 1234;
imageView.alpha = 0;
[self.window addSubview:imageView];
[self.window bringSubviewToFront:imageView];
// fade in the view
[UIView animateWithDuration:0.5 animations:^{
imageView.alpha = 1;
}];
}
- (void)applicationDidBecomeActive:(UIApplication *)application {
// grab a reference to our imageView
UIView *imageView = [self.window viewWithTag:1234];
// fade away imageView view from main view
[UIView animateWithDuration:0.5 animations:^{
imageView.alpha = 0;
} completion:^(BOOL finished) {
// remove when finished fading
[imageView removeFromSuperview];
}];
}