Question

我正在努力寻找一种在后台运行此方法的方法，以免中断UI。

我试图将UIImageView * ImgArray设置为NSArray或NSMutableArray，可以某种方式与GCD一起使用或以某种方式返回UIScrollView或UIImageArray。我一直在走向死胡同。

修改

我在

之前使用了错误的方法

 -(void)getSlideshow{
    //This populates string array from a URL
    //[self populateStringArray];
    NSString *prefix = @"http://newsongbismarck.com/images/announcements/";
    NSString *suffix = @".jpg";

    //NSUInteger count = [imageStringArray count];
    //get this from the website for now
    int number = (int)[imageStringArray count];
    int PageCount = number;

    //Setup scroll view
    UIScrollView *Scroller = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 265, 320, 200)];
    Scroller.backgroundColor = [UIColor clearColor];
    Scroller.pagingEnabled = YES;
    Scroller.contentSize = CGSizeMake(PageCount * Scroller.bounds.size.width, Scroller.bounds.size.height);

    //Setup Each View Size
    CGRect ViewSize = Scroller.bounds;

    int x = PageCount;
    int numb = 0;

    UIImageView *ImgArray[PageCount];

    //This loop adds the Images to a UIImageView within a UIScrollView
    while(x!=0){
        ImgArray[numb] = [[UIImageView alloc] initWithFrame:ViewSize];
        [ImgArray[numb] setImage:[self getSlideshowImages:[[prefix stringByAppendingString:imageStringArray[numb]]stringByAppendingString:suffix]]];

        //I haven't been able to make this work with dispatch_async main thread
        [Scroller addSubview:ImgArray[numb]];

        //Offset View Size
        ViewSize = CGRectOffset(ViewSize, Scroller.bounds.size.width, 0);

        x--;
        numb++;
    }



    CGRect newViewSize = Scroller.bounds;
    int NumberOfImages = 21;
    int i;
    for(i=0;i<NumberOfImages;i++){

        if(i == 0){
            //Setup first picture
            UIImageView *ImgView = [[UIImageView alloc] initWithFrame:newViewSize];
            NSString *FilePath = [NSString stringWithFormat:@"Page_%d.png", i];
            [ImgView setImage:[UIImage imageNamed:FilePath]];
            [Scroller addSubview:ImgView];
        }else{
            //Setup the rest of the pictures
            newViewSize = CGRectOffset(ViewSize, Scroller.bounds.size.width, 0);
            UIImageView *ImgView = [[UIImageView alloc] initWithFrame:newViewSize];
            NSString *FilePath = [NSString stringWithFormat:@"Page_%d.png", i];
            [ImgView setImage:[UIImage imageNamed:FilePath]];
            [Scroller addSubview:ImgView];
        }
    }

    //This adds the Scroller
    [self.view addSubview:Scroller];


}

EDIT2：

这是我对GCD的尝试，我不知道在哪里添加或设置滚动条视图或UIImageView ...... AFNetworking看起来很有希望。

代码仍然非常混乱。

-(void)showSlideShow{
[activity startAnimating];
[self populateStringArray];

NSString *URLString = @"http://newsongbismarck.com";
NSURL *url = [NSURL URLWithString:URLString];

if(url){
dispatch_queue_t slideQueue = dispatch_queue_create("Slide Show Queue",NULL);

dispatch_async(slideQueue, ^{

    // Perform long running process
    //[self populateStringArray];
    NSLog(@"Start background");
    NSString *prefix = @"http://newsongbismarck.com/images/announcements/";
    NSString *suffix = @".jpg";

    //NSUInteger count = [imageStringArray count];
    //get this from the website for now
    int number = (int)[imageStringArray count];
    int PageCount = number;

    //Setup scroll view
    UIScrollView *Scroller = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 265, 320, 200)];
    Scroller.backgroundColor = [UIColor clearColor];
    Scroller.pagingEnabled = YES;
    Scroller.contentSize = CGSizeMake(PageCount * Scroller.bounds.size.width, Scroller.bounds.size.height);

    //Setup Each View Size
    CGRect ViewSize = Scroller.bounds;

    int x = PageCount;
    int numb = 0;

    UIImageView *ImgArray[PageCount];

    while(x!=0){
        ImgArray[numb] = [[UIImageView alloc] initWithFrame:ViewSize];
        [ImgArray[numb] setImage:[self getSlideshowImages:[[prefix stringByAppendingString:imageStringArray[numb]]stringByAppendingString:suffix]]];
        //[Scroller addSubview:ImgArray[numb]];

        //Offset View Size
        ViewSize = CGRectOffset(ViewSize, Scroller.bounds.size.width, 0);

        x--;
        numb++;
    }

    CGRect newViewSize = Scroller.bounds;
    int NumberOfImages = 21;
    int i;
    for(i=0;i<NumberOfImages;i++){

        if(i == 0){
            //Setup first picture
            UIImageView *ImgView = [[UIImageView alloc] initWithFrame:newViewSize];
            NSString *FilePath = [NSString stringWithFormat:@"Page_%d.png", i];
            [ImgView setImage:[UIImage imageNamed:FilePath]];
            [Scroller addSubview:ImgView];
        }else{
            //Setup the rest of the pictures
            newViewSize = CGRectOffset(ViewSize, Scroller.bounds.size.width, 0);
            UIImageView *ImgView = [[UIImageView alloc] initWithFrame:newViewSize];
            NSString *FilePath = [NSString stringWithFormat:@"Page_%d.png", i];
            [ImgView setImage:[UIImage imageNamed:FilePath]];
            [Scroller addSubview:ImgView];
        }
    }


    NSLog(@"End of background tasks");
    dispatch_async(dispatch_get_main_queue(), ^{
        // Update the UI
        NSLog(@"Start main thread");
        int x = PageCount;
        int numb = 0;

        UIImageView *ImgArray[PageCount];

        while(x!=0){

            [Scroller addSubview:ImgArray[numb]];

            x--;
            numb++;
        }

        [self.view addSubview:Scroller];

        [activity stopAnimating];
    });
});

}else{
    loadLabel.text = @"Error - could not load images";

    [activity stopAnimating];
}
}

Answer 1

不是你要问的是不可能的，但是你考虑过一种更简单的方法吗？

UIImageView *imageView = [[UIImageView alloc] initWithFrame:self.view.frame];
[self.view addSubview:imageView];
imageView.animationImages = @[image1, image2, image3];
imageView.animationDuration = imageView.animationImages.count * 1.0f;   // 1 second per image
imageView.animationRepeatCount = 0;     // 0 means loop forever
[imageView startAnimating];

如何在后台线程中显示UIImageView数组

1 个答案: