NSRangeException隨機崩潰的應用程序

Question

1. 我的應用程序在_storeArray崩潰。
2. 在viewDidLoad中，有一個方法[self loadUrl]可以解析一個xml文件，然后添加一個字典[_storeArray addObject:dictionary] ；
3. 當輪播首先以某種方式reusingView調用，然后以[self loadUrl]調用時，發生崩潰。
4. 我已經添加了if(_storeArray)但是它仍然崩潰。

這是例外：

2013-04-06 09:33:35.254 Semhora[7347:907] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 0 beyond bounds for empty array'

這是代碼：

- (void)loadURL:(NSString *)newURL{

    // Create a success block to be called when the asyn request completes
    TBXMLSuccessBlock successBlock = ^(TBXML *tbxmlDocument) {


        [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];
        // If TBXML found a root node, process element and iterate all children
        if (tbxmlDocument.rootXMLElement)
        {
            // Obtain root element
            TBXMLElement * root = tbxml.rootXMLElement;
            if (root)
            {
                [_storeArray removeAllObjects];
                TBXMLElement * elem_PLANT = [TBXML childElementNamed:@"principal" parentElement:root];
                while (elem_PLANT !=nil)
                {
                    TBXMLElement * elem_title = [TBXML childElementNamed:@"title" parentElement:elem_PLANT];
                    NSString *titleName = [TBXML textForElement:elem_title];

//                    TBXMLElement * elem_artist = [TBXML childElementNamed:@"text" parentElement:elem_PLANT];
//                    NSString *artistName = [TBXML textForElement:elem_artist];

                    TBXMLElement * elem_thumb = [TBXML childElementNamed:@"thumb_url" parentElement:elem_PLANT];
                    NSString *thumbName = [TBXML textForElement:elem_thumb];

                    TBXMLElement * elem_photo1 = [TBXML childElementNamed:@"photo1" parentElement:elem_PLANT];
                    NSString *photo1Name = [TBXML textForElement:elem_photo1];

                    TBXMLElement * elem_photo2 = [TBXML childElementNamed:@"photo2" parentElement:elem_PLANT];
                    NSString *photo2Name = [TBXML textForElement:elem_photo2];

                    TBXMLElement * elem_photo3 = [TBXML childElementNamed:@"photo3" parentElement:elem_PLANT];
                    NSString *photo3Name = [TBXML textForElement:elem_photo3];

                    TBXMLElement * elem_photo4 = [TBXML childElementNamed:@"photo4" parentElement:elem_PLANT];
                    NSString *photo4Name = [TBXML textForElement:elem_photo4];

                    TBXMLElement * elem_photo5 = [TBXML childElementNamed:@"photo5" parentElement:elem_PLANT];
                    NSString *photo5Name = [TBXML textForElement:elem_photo5];

                    NSDictionary *dictionary = [[NSDictionary alloc]initWithObjects:@[titleName, thumbName, photo1Name, photo2Name, photo3Name, photo4Name, photo5Name] forKeys:@[@"title", @"thumb_url", @"photo1", @"photo2", @"photo3", @"photo4", @"photo5",]];
                    elem_PLANT = [TBXML nextSiblingNamed:@"principal" searchFromElement:elem_PLANT];
                    [_storeArray addObject:dictionary];
                   [self startLoading:dictionary];
                     [[NSOperationQueue mainQueue] addOperationWithBlock:^{ [_carousel reloadData]; }];
                }


            }

        }

    };

    // Create a failure block that gets called if something goes wrong
    TBXMLFailureBlock failureBlock = ^(TBXML *tbxmlDocument, NSError * error) {
        NSLog(@"Error! %@ %@", [error localizedDescription], [error userInfo]);
    };

    // Initialize TBXML with the URL of an XML doc. TBXML asynchronously loads and parses the file.
    tbxml = [[TBXML alloc] initWithURL:[NSURL URLWithString:newURL]
                               success:successBlock
                               failure:failureBlock];

}

- (UIView *)carousel:(iCarousel *)carousel viewForItemAtIndex:(NSUInteger)index reusingView:(UIView *)view
{
    //create new view if no view is available for recycling
    if (view == nil)
    {
        FXImageView *imageView = [[FXImageView alloc] initWithFrame:CGRectMake(0, 0, 200.0f, 200.0f)];
        imageView.contentMode = UIViewContentModeScaleAspectFit;
        imageView.asynchronous = YES;
        imageView.reflectionScale = 0.5f;
        imageView.reflectionAlpha = 0.25f;
        imageView.reflectionGap = 10.0f;
        imageView.shadowOffset = CGSizeMake(0.0f, 2.0f);
        imageView.shadowBlur = 5.0f;
        imageView.cornerRadius = 10.0f;
        view = imageView;
    }

    //show placeholder
    ((FXImageView *)view).processedImage = [UIImage imageNamed:@"placeholder.png"];

    //set image

    NSLog(@"%@", _storeArray);
    if (_storeArray) {

        NSDictionary *tempdic = [_storeArray objectAtIndex:0];

        switch (index) {
            case 0:
                [(FXImageView *)view setImageWithContentsOfURL:[NSURL URLWithString:[tempdic objectForKey:@"photo1"]]];
                break;
            case 1:
                [(FXImageView *)view setImageWithContentsOfURL:[NSURL URLWithString:[tempdic objectForKey:@"photo2"]]];
                break;
            case 2:
                [(FXImageView *)view setImageWithContentsOfURL:[NSURL URLWithString:[tempdic objectForKey:@"photo3"]]];
                break;
            case 3:
               [(FXImageView *)view setImageWithContentsOfURL:[NSURL URLWithString:[tempdic objectForKey:@"photo4"]]];
                break;
            case 4:
                [(FXImageView *)view setImageWithContentsOfURL:[NSURL URLWithString:[tempdic objectForKey:@"photo5"]]];
                break;
            default:
                break;
        }
    }

    return view;
}

Answer 1

1. 當前對_storeArray檢查僅檢查變量是否存在，而不檢查其中是否實際上有任何元素。 但是在檢查之后，您僅假設數組中有1個元素，而無需檢查是否為真。

   所以改變這個

    if (_storeArray) { 

   對此：

    if (_storeArray && [_storeArray count] > 0) { 

2. 另外，您假設字典將具有photo1等的密鑰。但是，如果沒有，則生成的URL將為空，因此視圖也可能會得到nil URL。

   我將更改如下：

    NSDictionary *tempdic = [_storeArray objectAtIndex:0]; NSString *tempObjKey = nil; switch (index) { case 0: tempObjKey = @"photo1"; break; case 1: tempObjKey = @"photo2"; break; case 2: tempObjKey = @"photo3"; break; case 3: tempObjKey = @"photo4"; break; case 4: tempObjKey = @"photo5"; break; default: break; } if (tempObjKey && [tempdic objectForKey:tempObjKey]) [(FXImageView *)view setImageWithContentsOfURL:[NSURL URLWithString:[tempdic objectForKey:tempObjKey]]]; } 

Answer 2

我需要知道一件事，您的解析是否發生在所有這些操作之前並成功返回一個數組（NSLog它），因為數組似乎是這里的問題。 您無法直接拿出第一個物體，因此必須保持防御，因此請執行以下操作。

 if (_storeArray) {

    if(_storeArray.count >0) {

    NSDictionary *tempdic = [_storeArray objectAtIndex:0];

    switch (index) { // all ur stmts }
    }}