在數組中找不到對象的位置？

Question

我有一個可以評估運動員的視圖控制器。導航欄中有一個下一個按鈕，用於加載下一位運動員。我試圖通過下面的代碼一步一步通過我的數組，但每次索引返回爲2？我不知道爲什麼！我錯過了什麼嗎？

-(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; 

} 

怪異的行爲是一個）視圖出現時，無論誰挖的指數是2，和b）不進入下一個運動員的eval，這是同一個人，這是索引中的最後一個人。

Answer 1

您正在將editIndex定義爲currentAthlete的索引。然後你從中減去1來得到索引，然後加1回到那個（索引爲++），最後你設置currentAthlete爲_athleteArray [index]，這將是你開始使用的同一名運動員。你應該可以通過不使用索引來修復它，只需使用editIndex即可。