NSUInteger不应该在格式字符串中使用吗? [英] NSUInteger should not be used in format strings?

问题描述

这是我的全部荣耀所在的代码:

Here's my code in all it's glory:

[NSString stringWithFormat:@"Total Properties: %d", (int)[inArray count]];

哪个让我收到Xcode 5.1警告:

Which gets me an Xcode 5.1 warning:

Values of type 'NSUInteger' should not be used as format arguments; add an explicit cast to 'unsigned long' instead

好，所以我很困惑.该值实际上是32位int，我将其强制转换为32位int.那么，这个NSUInteger在抱怨什么(我认为是这个数字)，为什么这个强制转换不能解决它?

Ok so I'm confused. The value really is a 32-bit int, and I cast it to a 32-bit int. So what is this NSUInteger it's complaining about (the count I assume) and why doesn't this cast fix it?

推荐答案

NSUInteger和NSInteger在32位(int)和64位(long)上具有不同的长度.为了使 one 格式说明符适用于两种体系结构，必须使用long说明符并将值强制转换为long:

NSUInteger and NSInteger are different lengths on 32-bit (int) and 64-bit (long). In order for one format specifier to work for both architectures, you must use a long specifier and cast the value to long:

Type    Format Specifier    Cast
----    ----------------    ----
NSInteger    %ld            long
NSUInteger   %lu            unsigned long

例如，您的代码变为:

[NSString stringWithFormat:@"Total Properties: %lu", (unsigned long)[inArray count]];

实际上，几乎没有什么工作要做，因为Xcode的Fix-It功能将自动为您完成此工作.

There is very little work to do, really, because Xcode's Fix-It feature will do this for you automatically.

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