Hide and present new modal view animated

UIViewController+Convenience.m

@implementation UIViewController (Convenience)

- (void)mn_hideCurrentModalControllerAndPresentController:(UIViewController *)controller
{
    if (self.modalViewController) {
        [self dismissModalViewControllerAnimated:YES];
        dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, 0.5 * NSEC_PER_SEC);
        dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
            [self presentModalViewController:controller animated:YES];
        });
    } else {
        [self presentModalViewController:controller animated:YES];   
    }
}