以同一方法处理和运行多个 ViewController

Question

我有一个 MainViewController，它有一个按钮 init。在按钮上单击图片开始动画，然后我创建一个不同 ViewController 的新实例，该实例运行 Web 请求并提取一些信息并将其推送到前面。我希望在中间视图控制器运行时图像是动画的。最后，一旦 MiddleViewController 完成，在同一个按钮方法中，我切换到第三个 ViewController。正如预期的那样，我收到以下错误：

    Warning: Attempt to present <ThirdViewController: 0x962b470> on <MainViewController: 0x986c200> while a presentation is in progress!
Unbalanced calls to begin/end appearance transitions

我该如何解决这个问题？我宁愿不移除中间的 ViewController 并将其代码集成到 MainViewController 中。

-(void)singleTapping:(UIGestureRecognizer *)recognizer
{

    UIImage *rot1 = [UIImage imageNamed:@"pic1.png"];
    UIImage *rot2 = [UIImage imageNamed:@"pic2.png"];
    UIImage *rot3 = [UIImage imageNamed:@"pic3.png"];
    UIImage *rot4 = [UIImage imageNamed:@"pic4.png"];

    self.scanclickedimage.animationImages = [[NSArray alloc] initWithObjects:rot1, rot2, rot3, rot4, nil];
    self.scanclickedimage.animationDuration = 0.6f;
    self.scanclickedimage.animationRepeatCount = HUGE_VALF;

    [self.scanclickedimage startAnimating];


    if (nextString == NULL || [nextString isEqualToString:@""]) {

        NSLog(@"Initializing MiddleViewController");
        MiddleViewController * middleViewController = [[MiddleViewController alloc] init];
        middleViewController.delegate = self;

        [self presentViewController:middleViewController animated:YES completion:nil];



    } else {
        ProductWebRequest *request = [[ProductWebRequest alloc] init];
        [request sendWebRequest:nextString];
    }






    NSString * storyboardName = @"MainStoryboard";
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:storyboardName bundle: nil];
    UIViewController * vc = [storyboard instantiateViewControllerWithIdentifier:@"ThirdViewController"];
    vc.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
    [self presentViewController:vc animated:YES completion:nil];




}

Answer 1

有时，当您同时呈现/推送超过 2 个视图控制器（或非常快）并且“动画”选项设置为“是”时，会出现此错误。

尝试像这样将动画设置为“NO”：

[self presentViewController:middleViewController animated:NO completion:nil];

或者做这样的事情：

[self presentViewController:middleViewController animated:YES completion:{
   [self presentViewController:vc animated:YES completion:nil];      
}];

您必须更新您的代码才能执行此操作。尝试将所有内容放在一个单独的方法中，如下所示：

-(void)singleTapping:(UIGestureRecognizer *)recognizer
{

    UIImage *rot1 = [UIImage imageNamed:@"pic1.png"];
    UIImage *rot2 = [UIImage imageNamed:@"pic2.png"];
    UIImage *rot3 = [UIImage imageNamed:@"pic3.png"];
    UIImage *rot4 = [UIImage imageNamed:@"pic4.png"];

    self.scanclickedimage.animationImages = [[NSArray alloc] initWithObjects:rot1, rot2, rot3, rot4, nil];
    self.scanclickedimage.animationDuration = 0.6f;
    self.scanclickedimage.animationRepeatCount = HUGE_VALF;

    [self.scanclickedimage startAnimating];


    if (nextString == NULL || [nextString isEqualToString:@""]) {

        NSLog(@"Initializing MiddleViewController");
        MiddleViewController * middleViewController = [[MiddleViewController alloc] init];
        middleViewController.delegate = self;

        [self presentViewController:middleViewController animated:YES completion:^{
            [self launchTest];
        }];

    } else {
        ProductWebRequest *request = [[ProductWebRequest alloc] init];
        [request sendWebRequest:nextString];
        [self launchTest];

    }
}

- (void)launchTest {

    NSString * storyboardName = @"MainStoryboard";
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:storyboardName bundle: nil];
    UIViewController * vc = [storyboard instantiateViewControllerWithIdentifier:@"ThirdViewController"];
    vc.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
    [self presentViewController:vc animated:YES completion:nil];
}