xcode NSArray 索引 1 超出空数组的界限
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原文地址: http://stackoverflow.com/questions/13260538/
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NSArray index 1 beyond bounds for empty array
提问by user1491987
-(IBAction)someMethod:(UIStepper *)sender{
int x=sender.value; //This is an integer from 0-8;
NSLog(@"%f",sender.value);
NSArray *rpmValues = [[NSArray alloc]initWithObjects:@"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",@"i", nil];
if (x<=[rpmValues count]) {
myLabel.text = [rpmValues objectAtIndex:x];
}
NSLog(@"%i",[rpmValues count]);
}
Above is my code, what I want to do is to change UILabel display by changing UIStepper. This is very straight forward. But when I change press the stepper value, it crashes:
上面是我的代码，我想要做的是通过改变UIStepper来改变UILabel的显示。这是非常直接的。但是当我改变按下步进值时，它崩溃了：
*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** - [__NSArrayM objectAtIndex:]: index 1 beyond bounds for empty array'
*** First throw call stack:
And the [rpmValue count] is 9. I really got confused. Can anyone help me?
而 [rpmValue count] 是 9。我真的很困惑。谁能帮我？
回答by WDUK
That code seems fine (see my comment on the question); your problem could arise from the use of
该代码看起来不错（请参阅我对问题的评论）；您的问题可能是由于使用
if (x<=[rpmValues count]) {
This will include the count of the array, which exceeds the index range by one. Use
这将包括数组的计数，该计数超出索引范围一。用
if (x < [rpmValues count]) {
回答by Tommy
At the very least if (x<=[rpmValues count])should be if (x<[rpmValues count]). Otherwise if you have an array with, say, two entities then you're allowing yourself to access indices 0, 1 and 2 — three possibilities in total.
至少if (x<=[rpmValues count])应该是if (x<[rpmValues count])。否则，如果您有一个包含两个实体的数组，那么您将允许自己访问索引 0、1 和 2 — 总共三种可能性。
Is it possible you've set a maximumValueon your stepper of '9' based on similar logic?
您是否可能maximumValue根据类似的逻辑在“9”的步进器上设置了 a ？
