当我使用 NSMutableArray 作为 Singleton 的属性时，将一些对象添加到 NSMutableArray 中。它压碎了

Question

这是我的示例代码：

-(IBAction)add:(id)sender {
//ShoppingManager sharedManager is a singleton
[[ShoppingManager sharedManager].onlineClassArray addObject:@(1)];
}

和 ShoppingManager.m 中的代码：

//singleton
+ (ShoppingManager *)sharedManager{
    static id instance;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        instance = [[self alloc]init];
    });
    return instance;
}


- (OnlineClassItemizeArray *)onlineClassArray{
    if (!_onlineClassArray) {
        _onlineClassArray = [OnlineClassItemizeArray array];
    }
    return _onlineClassArray;
}

和 ShoppingMananger.h:

@interface ShoppingManager : NSObject
@property(nonatomic,strong) OnlineClassItemizeArray * onlineClassArray;
+ (ShoppingManager*)sharedManager;
@end

我不知道这些有什么问题 codes.when 我在 mutableArray 中添加了一些对象，它停在这一行：（一个所有异常断点）

  _onlineClassArray = [OnlineClassItemizeArray array];

比这里压碎：

DISPATCH_INLINE DISPATCH_ALWAYS_INLINE DISPATCH_NONNULL_ALL DISPATCH_NOTHROW
DISPATCH_SWIFT3_UNAVAILABLE("Use lazily initialized globals instead")
void
_dispatch_once(dispatch_once_t *predicate,
        DISPATCH_NOESCAPE dispatch_block_t block)
{
    if (DISPATCH_EXPECT(*predicate, ~0l) != ~0l) {
        dispatch_once(predicate, block);//<---crushed here
    } else {
        dispatch_compiler_barrier();
    }
    DISPATCH_COMPILER_CAN_ASSUME(*predicate == ~0l);
}

这里是整个错误消息：

  2017-03-14 01:01:36.586 tesr1111[7075:1333259] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSMutableArray initWithCapacity:]: method only defined for abstract class.  Define -[OnlineClassItemizeArray initWithCapacity:]!'
*** First throw call stack:
(
    0   CoreFoundation                      0x00000001100c4d4b __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x000000010fb2621e objc_exception_throw + 48
    2   CoreFoundation                      0x00000001101357df __CFRequireConcreteImplementation + 255
    3   CoreFoundation                      0x00000001101241a7 -[NSMutableArray initWithCapacity:] + 39
    4   tesr1111                            0x000000010f54e6d0 -[ShoppingManager init] + 160
    5   tesr1111                            0x000000010f54e5f1 __32+[ShoppingManager sharedManager]_block_invoke + 65
    6   libdispatch.dylib                   0x0000000112eda0cd _dispatch_client_callout + 8
    7   libdispatch.dylib                   0x0000000112ebf1f8 dispatch_once_f + 501
    8   tesr1111                            0x000000010f54e588 +[ShoppingManager sharedManager] + 136
    9   tesr1111                            0x000000010f54de9d -[ViewController add:] + 61
    10  UIKit                               0x00000001104ea8bc -[UIApplication sendAction:to:from:forEvent:] + 83
    11  UIKit                               0x0000000110670c38 -[UIControl sendAction:to:forEvent:] + 67
    12  UIKit                               0x0000000110670f51 -[UIControl _sendActionsForEvents:withEvent:] + 444
    13  UIKit                               0x000000011066fe4d -[UIControl touchesEnded:withEvent:] + 668
    14  UIKit                               0x0000000110558545 -[UIWindow _sendTouchesForEvent:] + 2747
    15  UIKit                               0x0000000110559c33 -[UIWindow sendEvent:] + 4011
    16  UIKit                               0x00000001105069ab -[UIApplication sendEvent:] + 371
    17  UIKit                               0x0000000120cca481 -[UIApplicationAccessibility sendEvent:] + 93
    18  UIKit                               0x0000000110cf372d __dispatchPreprocessedEventFromEventQueue + 3248
    19  UIKit                               0x0000000110cec463 __handleEventQueue + 4879
    20  CoreFoundation                      0x0000000110069761 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
    21  CoreFoundation                      0x000000011004e98c __CFRunLoopDoSources0 + 556
    22  CoreFoundation                      0x000000011004de76 __CFRunLoopRun + 918
    23  CoreFoundation                      0x000000011004d884 CFRunLoopRunSpecific + 420
    24  GraphicsServices                    0x0000000113eb0a6f GSEventRunModal + 161
    25  UIKit                               0x00000001104e8c68 UIApplicationMain + 159
    26  tesr1111                            0x000000010f54e4df main + 111
    27  libdyld.dylib                       0x0000000112f2668d start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

如果有人能给我任何想法或帮助link。提前致谢。

Answer 1

您classNSMutableArray 的子NSMutableArray 不正确。它是一个 class 集群，需要实现最少的一组方法。

在这种情况下，您正在调用 initWithCapacity: 但尚未覆盖该方法。或者，更有可能的是，您正在调用调用该方法的通用方法 (init)。

正如异常所述：

2017-03-14 01:01:36.586 tesr1111[7075:1333259] 由于未捕获的异常 'NSInvalidArgumentException' 而终止应用程序，原因：' -[ NSMutableArray initWithCapacity:]：方法仅为抽象定义 class。定义 -[OnlineClassItemizeArray initWithCapacity:]!'

但是，子class集合 classes 是 code smell。这几乎从未完成过。在极少数情况下它是有意义的；你的是什么？

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