获取 NSString 变量的值
我有一个奇怪的问题。 pictureLink 是在 .h 中声明的全局变量
NSString *pictureLink;
}
@property(retain,nonatomic) NSString *pictureLink;
我写了这段代码
NSString * myPictureUrl=[NSString stringWithFormat:@"http://mywebsite.com/uploads/%@.jpg",hash];
pictureLink=myPictureUrl;
我有一个奇怪的结果，它必须是一个指针 或者
pictureLink=[NSString stringWithFormat:@"http://mywebsite.com/uploads/%@.jpg",hash];
我有 EXC_BAD_ACESS 错误
I have a weird problem.
pictureLink is a global variable declared in .h
NSString *pictureLink;
}
@property(retain,nonatomic) NSString *pictureLink;
i wrote this code
NSString * myPictureUrl=[NSString stringWithFormat:@"http://mywebsite.com/uploads/%@.jpg",hash];
pictureLink=myPictureUrl;
I have a strange result, it must be a pointer
Or
pictureLink=[NSString stringWithFormat:@"http://mywebsite.com/uploads/%@.jpg",hash];
i have EXC_BAD_ACESS error
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这是内存管理错误，您没有在代码中保留
myPictureUrl。[NSString stringWithFormat:@"http://mywebsite.com/uploads/%@.jpg",hash];返回一个自动释放的值，因此您有两个选择：pictureLink=myPictureUrl;应该类似于[self setPictureLink:myPictureUrl];。[myPictureUrl keep];，并且不要忘记稍后release它。考虑为您的项目使用 ARC（自动保留计数）。使用 ARC，编译器会处理保留计数，因此您不必这样做，实际上不允许这样做。有一个重构可以转换当前项目。
It's memory management fault, you're not retaining
myPictureUrlin your code.[NSString stringWithFormat:@"http://mywebsite.com/uploads/%@.jpg",hash];returns an autoreleased value, so you have two options:pictureLink=myPictureUrl;should look like[self setPictureLink:myPictureUrl];.[myPictureUrl retain];, and don't forget toreleaseit later.Consider using ARC (Automatic Retain Counting) for you project. With ARC the compiler takes care of retain counts so you don't have to, in fact aren't allowed to. There is a refactoring that will convert a current project.
您通过直接调用变量来绕过您的
@property，因此您的@property设置不会提供任何magic，例如保留和释放。您需要执行
self.pictureLink才能使用@property。为了避免直接访问我的变量的诱惑，我执行了以下操作
，
这样，如果我绕过@property，我真的非常想这样做。
但你需要一个非常非常充分的理由才能这样做，但即使如此，这可能还不是一个足够好的理由。
You are bypassing your
@propertyby calling directly the variable, so nomagicprovided by your@propertysettings is done, like retain and release.you need to do
self.pictureLinkto use the@property.To avoid the temptation of accessing directly my variable I do the following
and
That way if I go around the
@propertyI really, really wanted to do it.But you need a very, very, very good reason to do so, and event then, it may not be a good enough reason.