PLIST能否从不受信任的源安全读取?

例如,如果您希望字典中包含字符串键和NSNumbers作为值,则必须使用以下方法进行验证:

NSString *errorDescription = nil;
NSPropertyListFormat format = 0;
id topObject = [NSPropertyListSerialization propertyListFromData:plistData mutabilityOption:NSPropertyListImmutable format:&format errorDescription:&errorDescription];
NSDictionary *validDictionary = nil;
if ([topObject isKindOfClass:[NSDictionary class]]) {
    BOOL allNumbers = YES;
    for(id value in [topObject allValues]) {
        allNumbers = allNumbers && [value isKindOfClass:[NSNumber class]];
    }
    if (allNumbers) {
        validDictionary = topObject;
    }
}
return validDictionary;

NSDictionary 类别,以减少所需数量的 isKindOfClass

@interface NSDictionary (TypedDictionary)

-(NSArray *)arrayForKey:(NSString*)key;
-(NSString *)stringForKey:(NSString*)key;
-(NSDictionary *)dictionaryForKey:(NSString*)key;

@end


@implementation NSDictionary (TypedDictionary)

-(NSArray *)arrayForKey:(NSString*)key {
    NSArray *obj = [self objectForKey:key];
    return [obj isKindOfClass:[NSArray class]] ? obj : nil;
}
-(NSString *)stringForKey:(NSString*)key {
    NSString *obj = [self objectForKey:key];
    return [obj isKindOfClass:[NSString class]] ? obj : nil;
}
-(NSDictionary *)dictionaryForKey:(NSString*)key {
    NSDictionary *obj = [self objectForKey:key];
    return [obj isKindOfClass:[NSDictionary class]] ? obj : nil;
}
@end