NSUserDefaults 不会存储我的 NSStrings

Question

我试图在我的 NSUserDefaults 中存储几个字符串...无法弄清楚我做错了什么...

-(IBAction)addToFavorite:(id)sender {
    NSMutableArray* favoritedAlready = [[[NSUserDefaults standardUserDefaults] objectForKey:@"favorites"] mutableCopy];

NSLog(@"%@",favoritedAlready);


    if (![favoritedAlready containsObject:indexPathRowString]) {
        [favoritedAlready addObject:indexPathRowString];
        [[NSUserDefaults standardUserDefaults] setObject:favoritedAlready forKey:@"favorites"];
        [[NSUserDefaults standardUserDefaults] synchronize];
        favoritMarkerad.image = [UIImage imageNamed:@"StarFilled.png"];}

    else {
        [favoritedAlready removeObject:indexPathRowString];
        [[NSUserDefaults standardUserDefaults] setObject:favoritedAlready forKey:@"favorites"];
        [[NSUserDefaults standardUserDefaults] synchronize];
        favoritMarkerad.image = [UIImage imageNamed:@"StarEmpty.png"];
   }

当我尝试在另一个视图控制器中加载数组时没有任何反应..

(.h)
NSMutableArray *favorites_;
@property (nonatomic, retain) NSMutableArray *favorites_;

(.m)
@synthesize favorites_;

-(void)makeData{

NSMutableArray* favoritedAlready = [[NSUserDefaults standardUserDefaults] objectForKey:@"favorites"];
    [[NSUserDefaults standardUserDefaults] synchronize];

    favorites_ = favoritedAlready;}

“NSLog(@”% @“，已收藏）；”给出“2012-01-25 14:53:26.360 myApp[2752:1be03] (null)” 有什么想法吗？

Answer 1

根据您的评论，问题是您的 NSUserDefaults 中任何时候都没有名为“favorites”的数组。如果它不存在，您可能想创建一个。所以：

-(IBAction)addToFavorite:(id)sender {
    // get a mutable copy of the stored array, if there is one
    NSMutableArray* favoritedAlready = [[[NSUserDefaults standardUserDefaults] 
                     objectForKey:@"favorites"] mutableCopy];

    // if there wasn't a stored array then go ahead and create one to store
    if(!favoritedAlready)
        favoritedAlready = [NSMutableArray array];

    /* ... rest of stuff here ... */
    if (![favoritedAlready ...

Answer 2

NSMutableArray 在第一点处为 (null)，因此您可以

    if (favoritedAlready == nil) {
        favoritedAlready = [[NSMutableArray alloc] init];
    }

在 mutableCopy 方法之后执行此操作。
因此，您将向 NSMutableArray 添加值，而不是将其添加到（空）对象

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就像 Tommy 所说的