Disable the return key of keyboard

disableReturnKey.m

-(void)disableReturnKey{
    // Locate non-UIWindow.
    UIWindow *keyboardWindow = nil;
    for (UIWindow *testWindow in [[UIApplication sharedApplication] windows]) {
        if (![[testWindow class] isEqual:[UIWindow class]]) {
            keyboardWindow = testWindow;
            break;
        }
    }
    
    // Locate UIKeyboard.  
    UIView *foundKeyboard = nil;
    for (UIView *possibleKeyboard in [keyboardWindow subviews]) {
        
        // iOS 4 sticks the UIKeyboard inside a UIPeripheralHostView.
        if ([[possibleKeyboard description] hasPrefix:@"<UIPeripheralHostView"]) {
            possibleKeyboard = [[possibleKeyboard subviews] objectAtIndex:0];
        }                                                                                
        
        if ([[possibleKeyboard description] hasPrefix:@"<UIKeyboard"]) {
            foundKeyboard = possibleKeyboard;
            break;
        }
    }
    
    [foundKeyboard performSelector:@selector(setReturnKeyEnabled:) withObject:NO];
}