如何让NSString显示数组计数

I need to display the count of a array in a label. To do that I need to pass the array.count to an NSString. This is what I have tried:

我需要在标签中显示数组的计数。为此,我需要将array.count传递给NSString。这是我尝试过的:

if (myArray.count > 0 ) {
   NSString *newString = @"Array count = %@", myArray.count; 
   [_myLabel setText:newString];
}

It didn't work. I also tried to replace the NSString with an NSMutableString, no results there. So my question is, how do i do that?

它没用。我也尝试用NSMutableString替换NSString,没有结果。所以我的问题是,我该怎么做?

I also tried to replace the %@, for %lu, and then add the (unsigned long) before the array count (just like I do to display the array count on a NSlog), but this did not work either.

我还尝试将%@替换为%lu,然后在数组计数之前添加(unsigned long)(就像我在NSlog上显示数组计数一样),但这也不起作用。

3 个解决方案

#1

NSString *newString = [NSString stringWithFormat:@"Array count = %d", myArray.count];

#2

Like this:

NSString *newString = [NSString stringWithFormat:@"Array count = %lu", myArray.count];

The reason why your code even compiled is somewhat strange: Objective C interpreted your expression as a comma expression, ignoring the @"Array count = %@" portion, and assigning the value of myArray.count to newString.

您编写代码的原因有点奇怪:Objective C将您的表达式解释为逗号表达式,忽略@“Array count =%@”部分,并将myArray.count的值赋给newString。

This leads to undefined behavior when setText: tries to copy something from the "pointer" pointed to by myArray.count.

当setText:尝试从myArray.count指向的“指针”复制某些内容时,这会导致未定义的行为。

#3

If you want to be modern:

如果你想成为现代的:

NSString *str = [@(array.count) stringValue];

#1

NSString *newString = [NSString stringWithFormat:@"Array count = %d", myArray.count];

#2