问题描述

iphone-从block中返回整数

要从调用的block中返回整数：

-(NSInteger)globalRecord
{
    __block NSInteger globalRecord = 0;

    [GKLeaderboard loadLeaderboardsWithCompletionHandler:^(NSArray *leaderboards, NSError *error) {
        GKLeaderboard *globalTaps = nil;
        for (GKLeaderboard *lb in leaderboards) if ([lb.category isEqualToString:kGlobalLeaderboard]) globalTaps = lb;

        [globalTaps loadScoresWithCompletionHandler:^(NSArray *scores, NSError *error) {
            if ([scores count] != 0)
            {
                GKScore *topScore = [scores objectAtIndex:0];
                globalRecord = topScore.value;
                //42 here
            }

        }];
    }];

    //0 here

    return globalRecord;
}

从游戏中心的排行榜返回最高分，需求是只要接收到分数方法就返回给我，但是没返回成功。

比如在block中最高分是42，但是在block外值就是0。

请高手帮忙解答。

解决方案

要获取globalRecord值应该使用一个回调。

-(void)globalRecord
{
    __block NSInteger globalRecord = 0;

    [GKLeaderboard loadLeaderboardsWithCompletionHandler:^(NSArray *leaderboards, NSError *error) {
        GKLeaderboard *globalTaps = nil;
        for (GKLeaderboard *lb in leaderboards) if ([lb.category isEqualToString:kGlobalLeaderboard]) globalTaps = lb;

        [globalTaps loadScoresWithCompletionHandler:^(NSArray *scores, NSError *error) {
            if ([scores count] != 0)
            {
                GKScore *topScore = [scores objectAtIndex:0];
                globalRecord = topScore.value;
                [self globalRecordRetrieved:globalRecord];
                //42 here
            }

        }];
    }];
}

- (void)globalRecordRetrieved:(NSInteger)record{
    NSLog(@"%d",record); //42 here
}

解决方案二：

请参见我先前的回答，你的问题同　　等待AFJSONRequestOperation完成

要解决你的问题，也很简单，需要重新修改一下你的globalRecord方法,改成无返回值的方法

-(void)globalRecordWithBlock:(void(^)(int record))processResult
{
    __block NSInteger globalRecord = 0;

    [GKLeaderboard loadLeaderboardsWithCompletionHandler:^(NSArray *leaderboards, NSError *error) {
        GKLeaderboard *globalTaps = nil;
        for (GKLeaderboard *lb in leaderboards) if ([lb.category isEqualToString:kGlobalLeaderboard]) globalTaps = lb;

        [globalTaps loadScoresWithCompletionHandler:^(NSArray *scores, NSError *error) {
            if ([scores count] != 0)
            {
                GKScore *topScore = [scores objectAtIndex:0];
                globalRecord = topScore.value;
                //42 here
            }
            processResult(globalRecord);  ///将结果回调给调用者
        }];
    }];

}

调用：

[obj globalRecordWithBlock^(int record) {
       NSLog(@"global record is :%d",record);
}];