ios - 无法找到对象在数组中的位置？

Question

我有一个 View Controller ，可以在其中评估运动员。导航栏中有一个下一步按钮，应该加载下一个运动员。我正在尝试使用以下代码单步执行我的数组，但每次索引都返回 2？我不知道为什么!我错过了什么吗？

-(void)viewDidAppear:(BOOL)animated{
    NSUInteger editIndex = [_athleteArray indexOfObject:_currentAthlete];
    NSUInteger index = editIndex-1;

    Athlete *count = _athleteArray[index];

    NSLog(@"Current Athlete:%@ Index: %lu",count,(unsigned long)index);
}


-(void)whenNextButtonIsTapped{
//stuff
    NSUInteger editIndex = [_athleteArray indexOfObject:_currentAthlete];
    NSUInteger index = editIndex-1;

    Athlete *count = _athleteArray[index];

    NSLog(@"Current Athlete:%@ Index: %lu",count,(unsigned long)index);

    if(index <= ((_athleteArray.count)-1)){
        index++;
        _currentAthlete = _athleteArray[index];
        _evalSelected = [self getMostRecentEval];
        [self updateInformation];
        NSLog(@"Index after being smaller than the array count: %lu",(unsigned long)index);
    }
    else{
        if(index == ((_athleteArray.count)-1)){
            _evalSelected = [self getMostRecentEval];
            [self updateInformation];
            index=0;
            NSLog(@"Index after being equal to array count: %lu",(unsigned long)index);
        }
    }
    self.title = [NSString stringWithFormat:@"%@'s Evaluation",_evalSelected.whosEval.full];


}

}


-(Eval *)getMostRecentEval{
    NSFetchRequest *request = [[NSFetchRequest alloc] init];

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"whosEval == %@", _currentAthlete];
    [request setPredicate:predicate];
    NSEntityDescription *eval = [NSEntityDescription entityForName:@"Eval" inManagedObjectContext:_managedObjectContext];
    [request setEntity:eval];



    NSSortDescriptor *sortDescriptor =
    [[NSSortDescriptor alloc] initWithKey:@"date_recorded"
                                ascending:NO
                                 selector:@selector(localizedCaseInsensitiveCompare:)];
    NSArray *sortDescriptors = [[NSArray alloc]initWithObjects:sortDescriptor, nil];
    [request setSortDescriptors:sortDescriptors];

    NSError *error = nil;

    NSMutableArray *mutableFetchResults = [[_managedObjectContext executeFetchRequest:request error:&error] mutableCopy];
    if (mutableFetchResults == nil){
        //handle error
    }

    NSMutableArray *lastEvalArray = mutableFetchResults;

    return lastEvalArray.firstObject;

}

奇怪的行为是a)当 View 出现时，无论谁被点击，索引都是2。b)它不会进入下一个运动员的评估，它是同一个人，并且是最后一个人索引。

Answer 1

您正在将 editIndex 定义为当前运动员的索引。然后从中减去 1 以获得索引，然后加 1(使用索引++)，最后将 currentAthlete 设置为 _athleteArray[index]，这将是您开始时使用的同一运动员。您应该能够通过根本不使用索引来修复它，只需使用 editIndex。