如果在数组中找不到任何内容，为什么此循环会导致崩溃

我完全迷失了方向，甚至不确定如何表达这个问题。我有一个循环，如下所示。如果if循环中的语句证明为trueindexPath分配了值，则循环完成（_samplePictures数组中有49个对象）if (found)，然后输入，然后加载找到的数据。如果条件不成立，并且未找到任何内容而不是进入if(!found)应用程序，则崩溃。我已经尝试了这种当前编码方案的各种结构。我什至删除了循环，并输入了if(!found)它应该执行的操作。（ooooodddddddd）

该语句位于的viewDidLoad正上方（if语句不是viewDidLoad），它是if确定的内容的语句_samplePictures。

知道数组中的图像定义如下可能很有用：

#define IMG_71          [UIImage imageNamed:@"imagename.jpg"]

数组的结构如下：

_samplePictures = @[@{@"Image": IMG_71, @"Title" : @"title of item", @"Description" : @"complete description of item"}];

if (fromKitInstructions)
{
    int i = 0;

    NSIndexPath *indexPath;
    found = FALSE;

    while(i <= _samplePictures.count)
    {
        if([_samplePictures[i] objectForKey:@"Title"] == instructionName)
        {
            indexPath  = [NSIndexPath indexPathForRow:i inSection:0];
            i = 50;
            found = TRUE;
        }
        else
        {
            i++;
        }
    }

    if(found)
    {
        [self tableView:self.tableView didSelectRowAtIndexPath:indexPath];
    }

    if(!found)
    {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:instructionName message:@"We are sorry but the Kit ID you searched for could not be found. Press the Back button to return to the Instructions you were viewing." delegate:self cancelButtonTitle:@"OK" otherButtonTitles:@"Say Hello",nil];
        [alert show];
    }
}

这是使您进入此代码的按钮：

-(void)goTo:(id)sender
{
    ViewController *goGallery = [[ViewController alloc] initWithNibName:@"ViewController" bundle:[NSBundle mainBundle]];
    goGallery.setFlag = NO;
    goGallery.fromKitInstructions = YES;
    goGallery.instructionName = instructionName;
    [self.navigationController pushViewController:goGallery animated:YES];

}

调试器显示以下内容：

2014-05-30 15:08:37.873 TechBook[3932:60b] [INFO] <HomeViewController: 0xc67bb00> loaded
2014-05-30 15:14:24.268 TechBook[3932:3c03] void SendDelegateMessage(NSInvocation *): delegate (webView:decidePolicyForMIMEType:request:frame:decisionListener:) failed to return after waiting 10 seconds. main run loop mode: kCFRunLoopDefaultMode
2014-05-30 15:14:43.204 TechBook[3932:60b] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayI objectAtIndex:]: index 49 beyond bounds [0 .. 48]'
*** First throw call stack:
(
    0   CoreFoundation                      0x01f3d1e4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x01cbc8e5 objc_exception_throw + 44
    2   CoreFoundation                      0x01ef18b2 -[__NSArrayI objectAtIndex:] + 210
    3   CoreFoundation                      0x01fbbf48 -[NSArray objectAtIndexedSubscript:] + 40
    4   TechBook                            0x0000ae3d -[ViewController viewDidLoad] + 22381
    5   UIKit                               0x0088e33d -[UIViewController loadViewIfRequired] + 696
    6   UIKit                               0x0088e5d9 -[UIViewController view] + 35
    7   UIKit                               0x008a8942 -[UINavigationController _startCustomTransition:] + 778
    8   UIKit                               0x008b58f7 -[UINavigationController _startDeferredTransitionIfNeeded:] + 688
    9   UIKit                               0x008b64e9 -[UINavigationController __viewWillLayoutSubviews] + 57
    10  UIKit                               0x009f70d1 -[UILayoutContainerView layoutSubviews] + 213
    11  UIKit                               0x007de964 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 355
    12  libobjc.A.dylib                     0x01cce82b -[NSObject performSelector:withObject:] + 70
    13  QuartzCore                          0x001f145a -[CALayer layoutSublayers] + 148
    14  QuartzCore                          0x001e5244 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 380
    15  QuartzCore                          0x001e50b0 _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 26
    16  QuartzCore                          0x0014b7fa _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 294
    17  QuartzCore                          0x0014cb85 _ZN2CA11Transaction6commitEv + 393
    18  QuartzCore                          0x0020a5b0 +[CATransaction flush] + 52
    19  UIKit                               0x0076d9bb _UIApplicationHandleEventQueue + 13095
    20  CoreFoundation                      0x01ec677f __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15
    21  CoreFoundation                      0x01ec610b __CFRunLoopDoSources0 + 235
    22  CoreFoundation                      0x01ee31ae __CFRunLoopRun + 910
    23  CoreFoundation                      0x01ee29d3 CFRunLoopRunSpecific + 467
    24  CoreFoundation                      0x01ee27eb CFRunLoopRunInMode + 123
    25  GraphicsServices                    0x036d75ee GSEventRunModal + 192
    26  GraphicsServices                    0x036d742b GSEventRun + 104
    27  UIKit                               0x0076ff9b UIApplicationMain + 1225
    28  TechBook                            0x00003b1d main + 141
    29  libdyld.dylib                       0x027ee701 start + 1
    30  ???                                 0x00000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException