NSArrayM objectAtIndex:超出界限的索引6

Question

我正在开发iOS应用程序。值存储在Array上，但是当我运行app时，它会崩溃，数组索引超出了范围。请提前帮助和感谢。

代码：

daysOfWeek = [NSArray arrayWithObjects:@"Monday",@"Tuesday",@"Wednesday",@"Thursday",@"Friday",@"Saturday",@"Sunday", nil];
    for (int i = 0; i<= [_daysOfWeek count]; i++) {
   _mondayView=[[UIView alloc]initWithFrame:CGRectMake(45, 300  , 830, 30.0)];
         [_mondayView setBackgroundColor:[UIColor colorWithRed:190.0/255.0 green:190.0/255.0 blue:194.0/255.0 alpha:1.0]];
        [_weeklyView addSubview:_mondayView];

        UILabel *daysLabel = [[UILabel alloc]initWithFrame:CGRectMake(65.0f, 300.0f, 120.0f, 30.0f)];
        daysLabel.backgroundColor = [UIColor blueColor];
        daysLabel.text = [NSString stringWithFormat:@"%@",[_daysOfWeek objectAtIndex:i]];
        [_weeklyView addSubview:daysLabel];

    }

崩溃日志：

2016-11-14 11:48:41.266 FH Harvey[1839:67640] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayI objectAtIndex:]: index 7 beyond bounds [0 .. 6]'
*** First throw call stack:
(
    0   CoreFoundation                      0x000000011101934b __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x000000011065d21e objc_exception_throw + 48
    2   CoreFoundation                      0x0000000110f53eeb -[__NSArrayI objectAtIndex:] + 155
    3   FH Harvey                           0x000000010fe1ee62 -[FHWeeklyViewController viewDidLoad] + 1026
    4   UIKit                               0x00000001115ddc99 -[UIViewController loadViewIfRequired] + 1258
    5   UIKit                               0x00000001115e4102 -[UIViewController __viewWillAppear:] + 118
    6   UIKit                               0x000000011160efbf -[UINavigationController _startCustomTransition:] + 1290
    7   UIKit                               0x000000011161fc34 -[UINavigationController _startDeferredTransitionIfNeeded:] + 697
    8   UIKit                               0x0000000111620dc7 -[UINavigationController __viewWillLayoutSubviews] + 58
    9   UIKit                               0x0000000111817d6f -[UILayoutContainerView layoutSubviews] + 223
    10  UIKit                               0x0000000111500f50 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 1237
    11  QuartzCore                          0x000000010ffbdcc4 -[CALayer layoutSublayers] + 146
    12  QuartzCore                          0x000000010ffb1788 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 366
    13  QuartzCore                          0x000000010ffb1606 _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 24
    14  QuartzCore                          0x000000010ff3f680 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 280
    15  QuartzCore                          0x000000010ff6c767 _ZN2CA11Transaction6commitEv + 475
    16  UIKit                               0x0000000111435a97 _UIApplicationFlushRunLoopCATransactionIfTooLate + 206
    17  UIKit                               0x0000000111c456e0 __handleEventQueue + 5672
    18  CoreFoundation                      0x0000000110fbe311 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
    19  CoreFoundation                      0x0000000110fa359c __CFRunLoopDoSources0 + 556
    20  CoreFoundation                      0x0000000110fa2a86 __CFRunLoopRun + 918
    21  CoreFoundation                      0x0000000110fa2494 CFRunLoopRunSpecific + 420
    22  GraphicsServices                    0x00000001163a0a6f GSEventRunModal + 161
    23  UIKit                               0x000000011143c964 UIApplicationMain + 159
    24  FH Harvey                           0x000000010fe221bf main + 111
    25  libdyld.dylib                       0x000000011491368d start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb) 

Answer 1

问题在于您的for循环。数组索引以0开头，因此将for循环更改为：

for (int i = 0; i < [_daysOfWeek count]; i++) {

您使用的是i<=[_daysOfWeek count]，这也是导致index 7 beyond bounds [0 .. 6]崩溃的原因。

与使用for循环不同，您可以使用for each循环，它很容易实现，而且它永远不会导致索引超出绑定崩溃。

 for (NSString* str in _daysOfWeek) {
     NSLog(@"%@",str);
 }

Answer 2

迪帕克·库马尔刚刚证实了你的逻辑。您的数组有7个值，并且要迭代8次。只要改变逻辑

for (int i = 0; i < [_daysOfWeek count]; i++)

或

使用Nirav描述的for each循环(最优化的方法)。

快乐编码..。

Answer 3

只需将循环逻辑从i <= [_daysOfWeek count]更改为i < [_daysOfWeek count]就可以解决问题。但是，为了避免将来出现这样的错误，我建议您使用NSArray的NSArray方法。它可以通过以下方式进行：

NSArray *daysOfWeek = [NSArray arrayWithObjects:@"Monday",@"Tuesday",@"Wednesday",@"Thursday",@"Friday",@"Saturday",@"Sunday", nil];
[daysOfWeek enumerateObjectsUsingBlock:^(NSString*  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {

}];