Question

所以，我有一个数组，我从名为“choice”的文件中检索。我的问题是每次进入高分榜时，它只显示最高分。此外，它在下次加载时只保留数组中的两个元素。这是我的代码：

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0]; 
NSString *choice = [NSString stringWithFormat:@"%@/userschoice", documentsDirectory];
NSMutableArray *array = [NSMutableArray arrayWithContentsOfFile:choice];
NSArray *sortedHighScores = [array sortedArrayUsingSelector:@selector(compare:)];
NSMutableArray *finalArray = [[NSMutableArray alloc] init];



if ([array count]!= 0)
{   
    [array removeAllObjects];


    for (id someObject in [sortedHighScores reverseObjectEnumerator])
    {
        [finalArray addObject:someObject];

    }

    if ([array count]>1){
        NSNumber *highscore3 = [finalArray objectAtIndex:1];
        highscore2Label.text = [NSString stringWithFormat:@"2. %@ seconds",[highscore3 stringValue]];
        [array addObject:highscore3];
    }
    if ([array count] > 2){
         NSNumber *highscore4 = [finalArray objectAtIndex:2];
         highscore3Label.text = [NSString stringWithFormat:@"3. %@ seconds",[highscore4 stringValue]];
         [array addObject:highscore4];

    }

    if ([array count] > 3){
        NSNumber *highscore5 = [finalArray objectAtIndex:3];
        highscore4Label.text = [NSString stringWithFormat:@"4. %@ seconds",[highscore5 stringValue]];
        [array addObject:highscore5];

    }



    if ([array count] > 4){
        NSNumber *highscore1 = [finalArray objectAtIndex:4];
        highscore5Label.text = [NSString stringWithFormat:@"5. %@ seconds",[highscore1 stringValue]];
        [array addObject:highscore1];
    }








    NSNumber *highscore2 = [finalArray objectAtIndex:0];
    highscore1Label.text = [NSString stringWithFormat:@"1. %@ seconds", [highscore2 stringValue]];
    [array addObject:highscore2];

    [array writeToFile:choice atomically:YES];
}

Answer 1

有这条线：

NSMutableArray *finalArray = [[NSMutableArray alloc] init];

....紧接着就是这个：

NSNumber *highscore2 = [finalArray objectAtIndex:0];

在第一行之后，finalArray是一个不包含任何对象的可变数组。在第二行中，您尝试在索引0处查找对象。除非您没有向finalArray添加任何对象，因此索引0处没有对象。这是非法的，因此您获得了异常和崩溃。我不确定你要用finalArray做什么，但你不能在数组中查找对象，除非它实际上包含一些对象。在进行查找之前，您应该检查数组计数。

索引错误时的数组对象

1 个答案: