Question

我使用四个按钮并随机按下按钮标签值以查看每次点击的不同值，因为我从数组中显示按钮的值，当我试图改变标签值时，我得到了跟随错误。

  *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[NSMutableArray exchangeObjectAtIndex:withObjectAtIndex:]: index 16 beyond bounds [0 .. 3]'

我的代码用于混洗标记值数组

words = [[NSMutableArray alloc] initWithObjects:@"1", @"2", @"3",@"4", nil] ;

 NSUInteger count = [questar count];
for (NSUInteger i = 0; i < count; ++i) {
    // Select a random element between i and end of array to swap with.
    NSInteger nElements = count - i;
    NSInteger n = (arc4random() % nElements) + i;
    [words exchangeObjectAtIndex:i withObjectAtIndex:n];
}

我应该做出什么改变？任何人都可以帮我解决

Answer 1

您必须先从quester中选择一张图片。您创建了索引n以从quester数组中获取对象？

words = [[NSMutableArray alloc] initWithObjects:@"1", @"2", @"3",@"4", nil] ;

NSUInteger count = [questar count];
for (NSUInteger i = 0; i < count; ++i) 
{
  // Select a random element between i and end of array to swap with.
  NSInteger nElements = count - i;
  NSInteger n = (arc4random() % nElements) + i;

  currentImage = [questar objectAtIndex:n];

  [words replaceObjectAtIndex:i withObject:currentImage];
}

或者，如果您想在数组中将count更改为：

NSUInteger count = [words count];

Answer 2

[words exchangeObjectAtIndex:i withObjectAtIndex:n];

在上面的陈述中，i和n都应该具有小于words计数的值（此处为4）。否则，你会得到例外。

Answer 3

以下内容：

NSInteger nElements = count - i;
NSInteger n = (arc4random() % nElements) + i;

应改为：

NSInteger nElements = count;
NSInteger n = (arc4random() % nElements);

洗牌数组未捕获异常

3 个答案: