删除所有以某个单词开头的NSUserDefaults

Question

有没有办法让我"浏览" NSUserDefault我的iPhone应用程序中所有s 的列表,只删除某些？

例如,我想获得所有以某个单词开头的关键名称.

像这样的东西:

[[NSUserDefaults standardUserDefaults] removeObjectForKey:@"Dog*"];

Answer 1

你可以看看dictionaryRepresentation.

这是一个实现,它NSPredicate用作通用匹配器以获得更大的灵活性.

@interface NSUserDefaults (JRAdditions)
- (void)removeObjectsWithKeysMatchingPredicate:(NSPredicate *)predicate;
@end

@implementation NSUserDefaults (JRAdditions)

- (void)removeObjectsWithKeysMatchingPredicate:(NSPredicate *)predicate {
   NSArray *keys = [[self dictionaryRepresentation] allKeys];
   for(NSString *key in keys) {
      if([predicate evaluateWithObject:key]) {
         [self removeObjectForKey:key];
      }
   }
}

@end

用法:

NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF BEGINSWITH %@", @"something"];
[[NSUserDefaults standardUserDefaults] removeObjectsWithKeysMatchingPredicate:pred];