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我的问题UISCrollView，UIScrollVIew在我的View2Controller，我UIScrollView有图像的缩略图，这是我从我ImagePicker挑选的图像（多张/单张图像）中导入的。我已经把我[self createScrollView];的viewDidAppear，所以在我第一次加载视图时UIScrollView，显然是因为我还没有选择图像。因此，在我选择它之后，我认为它没有更新。但是我的 images.count 正在我的调试器中更新。它没有在视图中更新，但是当我转到另一个ViewController然后再次返回时View2Controller，它会将图像加载到我的视图中UIScrollView，然后当我再次添加图像时它不会更新。为什么会这样？。

- (void)addImage:(UIImage *)image {
    [_images addObject:image];
    [_thumbs addObject:[image imageByScalingAndCroppingForSize:CGSizeMake(60, 60)]];
}

- (void) createScrollView {

    [scrollView setNeedsDisplay];
    int row = 0;
    int column = 0;
    for(int i = 0; i < _thumbs.count; ++i) {

        UIImage *thumb = [_thumbs objectAtIndex:i];
        UIButton * button = [UIButton buttonWithType:UIButtonTypeCustom];
        button.frame = CGRectMake(column*60+10, row*60+10, 60, 75);
        [button setImage:thumb forState:UIControlStateNormal];
        [button addTarget:self 
                   action:@selector(buttonClicked:) 
         forControlEvents:UIControlEventTouchUpInside];
        button.tag = i; 

        [scrollView addSubview:button];

        if (column == 4) {
            column = 0;
            row++;
        } else {
            column++;
        }

    }
   [scrollView setContentSize:CGSizeMake(300, (row+1) * 60 + 10)];
}

- (void)viewDidAppear:(BOOL)animated
{
    [self createScrollView];
}

- (void)viewDidLoad
{ 
     [super viewDidLoad];
        self.slotBg = [[UIView alloc] initWithFrame:CGRectMake(43, 370, 310, 143)];
        CAGradientLayer *gradient = [CAGradientLayer layer];
        gradient.frame = self.slotBg.bounds;
        gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor grayColor] CGColor], (id)[[UIColor whiteColor] CGColor], nil];
        [self.slotBg.layer insertSublayer:gradient atIndex:0];
        [self.view addSubview:self.slotBg];

        self.scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0.0f,0.0f,300.0f,130.0f)];
        [slotBg addSubview:self.scrollView];
            for(int i = 0; i <= 100; i++) 
            { 
                NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
                NSString *documentsDir = [paths objectAtIndex:0];

                NSString *savedImagePath = [documentsDir stringByAppendingPathComponent:[NSString stringWithFormat:@"oneSlotImages%d.png", i]]; 
                NSLog(@"savedImagePath=%@",savedImagePath);
                if([[NSFileManager defaultManager] fileExistsAtPath:savedImagePath]){ 
                    [self addImage:[UIImage imageWithContentsOfFile:savedImagePath]]; 
                    NSLog(@"file exists");
                } 
            } 
            NSLog(@"Count : %d", [_images count]);
}

编辑：（在这部分，图像不能从视图中删除。但在我的NSDocumentDirectory它被删除了，）

- (IBAction)buttonClicked:(id)sender {

        _clickedButton = (UIButton *)sender;
        UIAlertView *saveMessage = [[UIAlertView alloc] initWithTitle:@""
                                                              message:@"DELETE IMAGE？"
                                                             delegate:self
                                                    cancelButtonTitle:@"NO"
                                                    otherButtonTitles:@"YES", nil];
        [saveMessage show];  
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    NSString *title = [alertView buttonTitleAtIndex:buttonIndex];


    if([title isEqualToString:@"YES"]) {
        NSLog(@"YES was selected.");
        UIButton *button = _clickedButton1;
        [button removeFromSuperview];
        [_images1 objectAtIndex:button.tag];
        [_images1 removeObjectAtIndex:button.tag];

        NSFileManager *fileManager = [NSFileManager defaultManager];
        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];
        NSString *fullPath = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"firstSlotImages%lu.png", button.tag]];
        [fileManager removeItemAtPath: fullPath error:NULL];
        NSLog(@"image removed");       
    }
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2 回答 2

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viewDidAppear:仅在您查看视图时才调用。因此，当您“添加”图像时，您只是将它们添加到_images数组中，它们不会显示，因为您没有将它们添加到屏幕上。当您离开视图并返回时显示它们，因为viewDidAppear:再次被调用。

要解决此问题，请使用addImage:也将其添加到当前视图。

- (void)addImage:(UIImage *)image {
    int row = ?;
    int column = ?;
    [_images addObject:image];
    [_thumbs addObject:[image imageByScalingAndCroppingForSize:CGSizeMake(60, 60)]];
    UIImage *thumb = [_thumbs objectAtIndex:_thumbs.count-1];
    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    button.frame = CGRectMake(column*60+10, row*60+10, 60, 75);
    [button setImage:thumb 
            forState:UIControlStateNormal];
    [button addTarget:self 
               action:@selector(buttonClicked:) 
     forControlEvents:UIControlEventTouchUpInside];
    button.tag = _thumbs.count-1; 
    [scrollView addSubview:button];
}

唯一的问题当然是如何确定位置，也就是列和行。您可以通过获取最后一个拇指的框架并根据屏幕边界确定放置它的位置来做到这一点。

另一个修复

- (void)addImage:(UIImage *)image {
    [_images addObject:image];
    [_thumbs addObject:[image imageByScalingAndCroppingForSize:CGSizeMake(60, 60)]];
    [self createScrollView];
}
于 2012-06-25T02:27:35.063 回答
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您需要createScrollView在更新图像数组后调用。也许尝试移动[self createScrollView];到您的viewDidLoad方法的末尾？无论哪种方式，您都需要createScrollView在添加所有图像后调用。

于 2012-06-25T02:27:44.223 回答