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NSString 最美的创建方式也是最毒

三 06

NearApple技术 @, NSString, 常量NSString 3 Comments

今天睡觉前，看到一位学妹在淫淫网站上发了一篇关于Cocoa开发的技术文章，在这里http://blog.renren.com/blog/251384541/715015230，问为什么在代码中很少看到这样创建一个NSString对象的：

NSString *str = @”I LOVE TJAC”;

这是最简单最美丽地创建一个NSString对象的方法，估计也是列为开发人员最喜欢用的方式，而且应该很多人至今都还这样用。但是这样做其实是有很大的缺陷的。在官方String Programming Guide中是这样说的：

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The simplest way to create a string object in source code is to use the Objective-C @”…” construct:

NSString *temp = @”/tmp/scratch”;

Note that, when creating a string constant in this fashion, you should avoid using anything but 7-bit ASCII characters. Such an object is created at compile time and exists throughout your program’s execution. The compiler makes such object constants unique on a per-module basis, and they’re never deallocated, though you can retain and release them as you do any other object. You can also send messages directly to a string constant as you do any other string:

BOOL same = [@"comparison" isEqualToString:myString];

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所以如果你的程序中有这样的方式赶紧改过来吧，如果你觉得用类似与[NSString StringWith....]这样函数很麻烦，那么你可以些这样一个宏来简化你的工作：

#define OC(str) [NSString stringWithCString:(str) encoding:NSUTF8StringEncoding]

于是就可以方便使用了：NSLog(@”%@”, OC(“Hello World!”) );