Question

我有一个我想使用NSUserDefaults保存的自定义类对象，这就是我保存它的方式：

Shift.m

-(void)encodeWithCoder:(NSCoder*)encoder
{
    [encoder encodeObject:self.date forKey:@"date"];
    [encoder encodeObject:self.startTime forKey:@"startTime"];
    [encoder encodeObject:self.endTime forKey:@"endTime"];
}
- (id)initWithCoder:(NSCoder *)decoder {
    if(self = [super init]) {
        self.date = [decoder decodeObjectForKey:@"date"];
        self.startTime = [decoder decodeObjectForKey:@"startTime"];
        self.endTime = [decoder decodeObjectForKey:@"endTime"];
    }
    return self;
}

MyTableViewController.m ：

-(void)saveCustomObject:(id)object forKey:(NSString*)key
{
    NSData *encodedObject = [NSKeyedArchiver archivedDataWithRootObject:object];
    [[NSUserDefaults standardUserDefaults] setObject:encodedObject forKey:key];
}
-(NSArray*)getCustomObjectForKey:(NSString*)key
{
    NSData *encodedObject = [[NSUserDefaults standardUserDefaults] objectForKey:key];

    NSArray *shifts=[NSArray arrayWithObjects:[NSKeyedUnarchiver unarchiveObjectWithData:encodedObject], nil];

    return shifts;
}

它似乎在调试时工作正常，但是当我尝试访问其中一个对象属性时，例如在tableView: cellForRowAtIndexPath:上这样：

Shift *currentShift=[self.shifts objectForIndex:indexPath.row];
NSLog(@"%@",currentShift.startTime.description);

崩溃消息崩溃了：

2016-03-19 09:04:05.913 MyApp[9654:4249448] -[__NSArrayM startTime]: unrecognized selector sent to instance 0x7ff81b449c10
2016-03-19 09:04:05.924 MyApp[9654:4249448] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSArrayM startTime]: unrecognized selector sent to instance 0x7ff81b449c10'
*** First throw call stack:
(
    0   CoreFoundation                      0x000000010e3e9e65 __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x000000010de62deb objc_exception_throw + 48
    2   CoreFoundation                      0x000000010e3f248d -[NSObject(NSObject) doesNotRecognizeSelector:] + 205
    3   CoreFoundation                      0x000000010e33f90a ___forwarding___ + 970
    4   CoreFoundation                      0x000000010e33f4b8 _CF_forwarding_prep_0 + 120
    5   Mehuyavut count                     0x000000010d95a8e8 -[shiftsTableViewViewController tableView:cellForRowAtIndexPath:] + 600
    6   UIKit                               0x000000010e8efe43 -[UITableView _createPreparedCellForGlobalRow:withIndexPath:willDisplay:] + 766
    7   UIKit                               0x000000010e8eff7b -[UITableView _createPreparedCellForGlobalRow:willDisplay:] + 74
    8   UIKit                               0x000000010e8c4a39 -[UITableView _updateVisibleCellsNow:isRecursive:] + 2996
    9   UIKit                               0x000000010e8f901c -[UITableView _performWithCachedTraitCollection:] + 92
    10  UIKit                               0x000000010e8dfedc -[UITableView layoutSubviews] + 224
    11  UIKit                               0x000000010e84d4a3 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 703
    12  QuartzCore                          0x000000011231959a -[CALayer layoutSublayers] + 146
    13  QuartzCore                          0x000000011230de70 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 366
    14  QuartzCore                          0x000000011230dcee _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 24
    15  QuartzCore                          0x0000000112302475 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 277
    16  QuartzCore                          0x000000011232fc0a _ZN2CA11Transaction6commitEv + 486
    17  QuartzCore                          0x000000011233037c _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 92
    18  CoreFoundation                      0x000000010e315367 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
    19  CoreFoundation                      0x000000010e3152d7 __CFRunLoopDoObservers + 391
    20  CoreFoundation                      0x000000010e30af2b __CFRunLoopRun + 1147
    21  CoreFoundation                      0x000000010e30a828 CFRunLoopRunSpecific + 488
    22  GraphicsServices                    0x0000000111ba6ad2 GSEventRunModal + 161
    23  UIKit                               0x000000010e796610 UIApplicationMain + 171
    24  Mehuyavut count                     0x000000010d95b5af main + 111
    25  libdyld.dylib                       0x0000000110b2592d start + 1
    26  ???                                 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

任何人都知道为什么？

谢谢！

Answer 1

您使self.shifts成为NSArray，但您使用的objectForKey可用于词典。它不适用于阵列。我想你想要objectAtIndex。

Answer 2

您似乎希望Shift *currentShift=[self.shifts objectForIndex:indexPath.row]为您提供1 Shift个对象，但它真正做的是返回NSArray。你基本上在startTime中调用NSArray方法，因为它不存在，你的程序就失败了。

似乎NSLog(@"%@",currentShift.startTime.description)是这样做的。通过评论NSLog来确认。它不应该让你崩溃。

如果此假设正常，请检查[currentShift isKindOfClass:[NSArray class]]是否为真。

如果是，你在这一行中有一个错误：

NSArray *shifts=[NSArray arrayWithObjects:[NSKeyedUnarchiver unarchiveObjectWithData:encodedObject], nil];

您也没有真正展示- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section的样子。您必须在那里返回适当数量的条目。

编码后无法访问对象的属性（崩溃）

2 个答案: