ios - 如何从NSDictionary中删除包含“”的字符串

Question

我有用户信息字典，该信息从Web服务中获取。有些字段的内容是 private 的，因此包含NULL。我如何将值转换为空字符串，无论哪里存在null值，如以下字典中所示:

{
"about_me" = "<null>";
"contact_number" = 123456798798;
"display_name" = "err";
followers = 0;
following = 4;
gender = "-";
posts = 0;
"user_id" = 18;
username = charge;
website = "<null>";
}

Answer 1

更高级的解决方案:

@interface NSObject (NULLValidation)
- (BOOL)isNull ;
@end

@implementation NSObject (NULLValidation)

- (BOOL)isNull{
    if (!self) return YES;
    else if (self == [NSNull null]) return YES;
    else if ([self isKindOfClass:[NSString class]]) {
        return ([((NSString *)self)isEqualToString : @""]
                || [((NSString *)self)isEqualToString : @"null"]
                || [((NSString *)self)isEqualToString : @"<null>"]
                || [((NSString *)self)isEqualToString : @"(null)"]
                );
    }
    return NO;

}
@end


@interface NSDictionary (NullReplacement)
- (NSDictionary *) dictionaryByReplacingNullsWithString:(NSString*)string;
@end

@implementation NSDictionary (NullReplacement)

- (NSDictionary *) dictionaryByReplacingNullsWithString:(NSString*)string {
     NSMutableDictionary *replaced = [NSMutableDictionary dictionaryWithDictionary: self];

     NSString *blank = string;

    [self enumerateKeysAndObjectsUsingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {
        if ([obj isNull]) {
            [replaced setObject:blank forKey: key];
        }
        else if ([obj isKindOfClass: [NSDictionary class]]) {
            [replaced setObject: [(NSDictionary *) obj dictionaryByReplacingNullsWithString:string] forKey: key];
        }
    }];

    return replaced ;
}
@end