Question

我有一个视图控制器，可以对运动员进行评估。导航栏中有一个下一个按钮，可以加载下一个运动员。我试图通过以下代码逐步执行我的数组，但每次索引返回为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）当出现视图时，不管是谁被点击，索引是2.和b）它没有进入下一个运动员的评估，它是同一个人，它是最后一个人索引。

Answer 1

您正在将editIndex定义为currentAthlete的索引。然后从中减去1得到索引，然后将1加回（使用索引++），最后将currentAthlete设置为_athleteArray [index]，这将是您开始使用的同一个运动员。您应该能够通过不使用索引来修复它，只需使用editIndex。

在数组中找不到对象的位置？

1 个答案: