iOS-OC-把JSON字符串转化为字典

#pragma mark - 通过我要学ID获取融云的Token---异步
- (void)getRongCloudTokenWith5151StudyID:(NSString *)studyID completed:(void(^)(NSString *IMToken))completed{
NSString *url = [NSString stringWithFormat:@"users/%@/IMToken",studyID];
[LFNetWorkManager requestDataBaseWithURLByGET:url parameters:nil isWithToken:NO completed:^(id responseObject) {
NSString *dataStr = responseObject[@"data"];//JSON字符串
NSData *jsonData = [dataStr dataUsingEncoding:NSUTF8StringEncoding];//转化为data
NSDictionary *data = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers error:nil];//转化为字典
NSInteger code = [responseObject[@"code"] integerValue];
if (responseObject != nil && code==200) {
if (completed){
completed(data[@"token"]);
}
}else{
if (completed){
completed(nil);
}
}
}];
}