Objective-C是否使用字符串池? [英] Does Objective-C use string pooling?
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问题描述
我知道 Java 和
I know that Java and C# both use a string pool to save memory when dealing with string literals.
Objective-C是否使用任何此类机制?如果没有，为什么不呢?
Does Objective-C use any such mechanism? If not, why not?
推荐答案
是的，从不释放像@"Hello world"这样的字符串文字，它们指向相同的内存，这意味着指针比较是正确的.
Yes, string literals like @"Hello world" are never released and they point to the same memory which means that pointer comparison is true.
NSString *str1 = @"Hello world";
NSString *str2 = @"Hello world";
if (str1 == str2) // Is true.
这也意味着弱字符串指针不会更改为nil(在正常对象中会发生这种情况)，因为字符串文字不会被释放.
It also means that a weak string pointer won't change to nil (which happens for normal objects) since the string literal never gets released.
__weak NSString *str = @"Hello world";
if (str == nil) // This is false, the str still points to the string literal
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