[Solved] Why does my app crash when I tap the background?

From the chat with Jack, it appears the culprit of the crash was due to a method:

-(void)dismissKeyboard
{
    // ------------------------------------------------------
    // These variables appear to be NSString, so it crashes
    // ------------------------------------------------------
    [message resignFirstResponder];
    [contact1 resignFirstResponder];
    [contact2 resignFirstResponder];
    [contact3 resignFirstResponder];
}

So the solution was to simply change it to:

-(void)dismissKeyboard
{
    [self.view endEditing:YES];
}