模态的跳转底层

- (IBAction)click:(UIButton *)sender {
   #pragma mark 1.系统的modal，系统在跳转时控制器不会被销毁是
   因为有一个属性在强引用控制器self.presentedViewController
 NSLog(@"%@",self.presentedViewController);
OneViewController *one = [OneViewController new];
//当在modal时，会把窗口上面的view给移除掉，然后要modal控制器的view给添加到窗口上
// 如果当一个控制器被销毁，那么它的View的业务逻辑是无法处理的
// 控制器被销毁，控制器的View不一定被销毁（只要有枪指针指向它，就不会被销毁）
//    [self presentViewController:one animated:YES completion:^{
//      
//        NSLog(@"完成了模态");
//        
//    }];
#pragma mark 2.自定义的modal
CGRect frame = one.view.frame;
frame.origin.y = [UIScreen mainScreen].bounds.size.height;
one.view.frame = frame;
[[UIApplication sharedApplication].keyWindow addSubview:one.view];
//强引用控制器，防止被销毁
_oneVC = one;
[UIView animateWithDuration:0.5 animations:^{
    one.view.frame = self.view.frame;
    } completion:^(BOOL finished) {
      //[self.view removeFromSuperview];
    }];
 }

- (IBAction)back:(UIButton *)sender {
    #pragma mark 1.系统的modal
    //[self dismissViewControllerAnimated:YES completion:nil];
    #pragma mark 2.自定义的modal
    [UIView animateWithDuration:0.5 animations:^{
    CGRect frame = self.view.frame;
    frame.origin.y = [UIScreen mainScreen].bounds.size.height;
    self.view.frame = frame;
} completion:^(BOOL finished) {
    //[[UIApplication sharedApplication].keyWindow addSubview:self.view];
   }];
}