ios - 将对象添加到 NSArray 时程序崩溃

Question

我设置了以下 IBAction:

#define FAVORITES_KEY @"GraphViewController.Favorites"
- (IBAction)addToFavorites:(id)sender {
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSMutableArray *favorites = [defaults objectForKey:FAVORITES_KEY];
    if (!favorites) favorites = [NSMutableArray array];
    [favorites addObject:self.program];
    [defaults setObject:favorites forKey:FAVORITES_KEY];
    [defaults synchronize];
}

第一次调用这个 Action 时一切正常，对象被添加到我的数组并保存到 NSUserDefaults 没有问题，在第一次调用之后它会在添加到favorites 数组，如果我尝试跨过 break，它会这样说:

Single stepping until exit from function objc_exception_throw, 
which has no line number information.

Catchpoint 3 (exception thrown).

有人遇到过类似的问题或者可能知道发生了什么事吗？

Answer 1

NSUserDefaults 返回一个不可变数组，所以你需要转换它:

NSMutableArray *favorites = [[defaults objectForKey:FAVORITES_KEY] mutableCopy];
if (!favorites) favorites = [NSMutableArray new];
...
[favorites release];