問題描述
我目前正在使用 iOS 5 SDK 嘗試開發我的應用程序.我正在嘗試使 NSString 成為屬性，然后在 .m 文件中合成它(我之前已經這樣做了，沒有任何問題).現在，我遇到了這個問題:語義問題:屬性的合成 getter 遵循 Cocoa 命名約定以返回‘擁有’對象."
I'm currently using the iOS 5 SDK trying to develop my app. I'm trying to make an NSString a property, and then to synthesize it in the .m file (I have done this before with no issues). Now, I came across this: "Semantic Issue: Property's synthesized getter follows Cocoa naming convention for returning 'owned' objects."
這是我的代碼:.h
@interface ViewController : UIViewController {
NSString *newTitle;
}
@property (strong, nonatomic) NSString *newTitle;
.m
@synthesize newTitle;
有人知道我該如何解決這個問題嗎?謝謝！！
Does anyone have a clue how I could fix this? Thanks!!
推薦答案
我猜你使用的編譯器版本如下 內存管理規則 用于聲明的屬性——更具體地說，用于聲明的屬性的訪問器:
My guess is that the compiler version you’re using follows the memory management rules for declared properties, too — more specifically, for declared properties’ accessors:
如果您使用名稱以alloc"、new"、copy"或mutableCopy"開頭的方法創建對象，您將獲得該對象的所有權.
You take ownership of an object if you create it using a method whose name begins with "alloc", "new", "copy", or "mutableCopy".
一個名為 newTitle 的屬性在合成時會產生一個名為 -newTitle 的方法，因此會出現警告/錯誤.-newTitle 應該是 newTitle 屬性的 getter 方法，但是命名約定規定名稱以 new 開頭的方法返回一個對象它歸調用者所有，而 getter 方法則不然.
A property named newTitle, when synthesised, yields a method called -newTitle, hence the warning/error. -newTitle is supposed to be a getter method for the newTitle property, however naming conventions state that a method whose name begins with new returns an object that’s owned by the caller, which is not the case of getter methods.
您可以通過以下方式解決此問題:
You can solve this by:
重命名該屬性:
Renaming that property:
@property (strong, nonatomic) NSString *theNewTitle;
保留屬性名稱并指定不以特殊方法名稱前綴之一開頭的 getter 名稱:
Keeping the property name and specifying a getter name that doesn’t begin with one of the special method name prefixes:
@property (strong, nonatomic, getter=theNewTitle) NSString *newTitle;
同時保留屬性名和getter名，并告訴編譯器，即使getter名以new開頭，它也屬于none與 new 方法族相對的方法族:
Keeping both the property name and the getter name, and telling the compiler that, even though the getter name starts with new, it belongs to the none method family as opposed to the new method family:
#ifndef __has_attribute
#define __has_attribute(x) 0 // Compatibility with non-clang compilers
#endif
#if __has_attribute(objc_method_family)
#define BV_OBJC_METHOD_FAMILY_NONE __attribute__((objc_method_family(none)))
#else
#define BV_OBJC_METHOD_FAMILY_NONE
#endif
@interface ViewController : UIViewController
@property (strong, nonatomic) NSString *newTitle;
- (NSString *)newTitle BV_OBJC_METHOD_FAMILY_NONE;
@end
請注意，即使此解決方案允許您將 newTitle 保留為屬性名稱和 getter 名稱，但有一個名為 -newTitle 的方法不會返回調用者擁有的對象可能會讓其他閱讀您的代碼的人感到困惑.
Note that even though this solution allows you to keep newTitle as both the property name and the getter name, having a method called -newTitle that doesn’t return an object owned by the caller can be confusing for other people reading your code.
<小時>
作為記錄，Apple 已發布 Transitioning到 ARC 發行說明，他們在其中聲明:
您不能為屬性指定以 new 或 copy 開頭的名稱.
You cannot give a property a name that begins with
neworcopy.
他們已經被告知他們的陳述不太準確:罪魁禍首是 getter 方法名稱，而不是屬性名稱.
They’ve already been notified that their statement is not quite accurate: the culprit is the getter method name, not the property name.
2015 年 1 月 17 日我剛剛注意到一個 最近對 Clang 的提交建議上面的選項 3(使用 objc_method_family(none))，包括一個修復它，用于屬性名稱與特殊方法系列前綴之一匹配的一般情況.Xcode 最終可能會包含此更改.
Edit 17 Jan 2015: I’ve just noticed a recent commit to Clang that suggests option 3 above (using objc_method_family(none)), including a fix-it, for the general case where a property name matches one of the special method family prefixes. Xcode will likely incorporate this change eventually.
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