Question

How can I add a custom image (or hex color) to main.m that will be used in the whole application and all it’s views?

Answer 1

Don’t set it up in the main.m. Use your AppDelegate for that. A solution could look like this:

YourAppDelegate.h

YourAppDelegate : UIApplication <UIResponder> {
      UIImageView *myGlobalBackgroundImage;
}

@property (nonatomic, retain) UIImageView *myGlobalBackgroundImage;

YourAppDelegate.m

@implementation YourAppDelegate
@synthesize myGlobalBackgroundImage;

-.....applicationDidFinishLaunching....{
     myGlobalBackgroundImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"imagefilename.ext"]];
}

Then grab that ivar from within your UIViewController and add it as a subview in the viewDidLoad method.