ios - UIActivityIndi​​catorView在正确的时间显示

Question

我正在制作一个允许用户在IOS应用程序中输入数据的表格。该表格允许用户输入很多重复的数据。因此，有时该过程需要时间，因此我想在此过程中显示UIActivityIndi​​catorView。

不幸的是，微调器在过程结束时只出现一秒钟或更短的时间，而不是在预期的开始时出现。

有一些代码:

- (void) manageSpinner{
    spinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
    [spinner setCenter:CGPointMake(self.view.bounds.size.width/2.0, self.view.bounds.size.height/2.0)]; // I do this becau I'm in landscape mode
    UIImageView *imageView = [[UIImageView alloc]initWithFrame:self.tableView.bounds];
    UIImage *image = [UIImage imageNamed:@"dark_gradiant.jpg"];
    [imageView setImage:image];
    [imageView addSubview:spinner];
    [self.tableView addSubview:imageView];
    [spinner startAnimating];
}


//On click save by the user
- (IBAction)save:(id)sender{

    //Collect information from the form

    myObject.name = nameTF.text;

    [...]

    if(informations OK[...]){        
        //Manage spinner
        [self manageSpinner];

        //Add : this is the long process
        for (int i=0; i<nbRepeatChooseByUser; i++) {
            [myObject register];
        }

        //Call the delegate that will dismiss the form
        [self.delegate theSaveButtonOnTheAddMyObjectTVCWasTapped:self];
    }
}

微调器是在添加方法之前调用的，但似乎是在该过程之后设置的。

谢谢，

亚历山大(Alexandre)

Answer 1

Activity 指示器与您的长进程在同一线程上运行，因此动画不会按您希望的那样立即开始。尝试在后台线程中运行您的长进程。

if(informations OK[...]){        
    //Manage spinner
    [self manageSpinner];

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
        // Do your background process here
        //Add : this is the long process
        for (int i=0; i<nbRepeatChooseByUser; i++) {
            [myObject register];
        }

        dispatch_async(dispatch_get_main_queue(), ^{
            //This section will be called after your long process has been completed.

            //Call the delegate that will dismiss the form
            [self.delegate theSaveButtonOnTheAddMyObjectTVCWasTapped:self];
        });

    });

}