转换为自动引用计数（ARC）：“使用未声明的标识符”错误 [英] Conversion to Automatic Reference Counting (ARC): 'Use of undeclared identifier' errors

问题描述

在一个非常大的项目中，我使用了自动合成的属性：

In one of the very big projects I used auto-synthesized properties everywhere:

//MyClass.h file:
@interface MyClass : NSObject

@property (nonatomic, retain) NSString *deviceName;
@property (nonatomic, retain) NSString *deviceID;

@end

//MyClass.m file:
#import "MyClass.h"

@implementation ApplicationStatus
// no @synthesize used at all.

-(void)dealloc{

    [_deviceName release]; // gives errors only while converting to ARC with LLVM 5.0
    [_deviceID release];

    [super dealloc];
}

@end

上面的代码编译得很好非ARC模式，以及在ARC转换过程中在较旧的Xcode版本中。
当尝试使用最新的LLVM 5.0编译器（最新的Xcode）进行转换时，它给我几百万的错误：

The code above compiles well in non-ARC mode and also in older Xcode versions during ARC conversion process. When trying to convert in using newest LLVM 5.0 compiler (newest Xcode) it gives me millions of errors:

这是什么原因？我必须手动创建数百个实例变量并手动合成它们吗？这不是从写少代码的哲学退步的苹果广告在所有WWDCs？

What is the cause of this? Do I have to manually create hundreds of instance variables and @synthesize them manually now? Wouldn't that be step back from 'write less code' philosophy Apple advertised on all WWDCs?

推荐答案

问题。

按照苹果的指导，我虔诚地使用 self。 outside init 中的和 init 中的 _ 。

Following Apple's guidance, I religiously use self. outside init and _ in init. This breaks as you wrote, when migrating to ARC in Xcode 5.

我发现最简单的方法是：

I found the easiest way is to:

@synthesise deviceName = _deviceName;

更改所有引用只是愚蠢，痛苦和错误，甚至一个选项。

Changing all the references is just dumb, a pain, and wrong, and for read only variables, not even an option.

自动完成在设置synthesise语句时非常聪明，你只需要它们来访问 init 。

The autocomplete is pretty smart in setting up the synthesise statements, and you only need them for the stuff you're going to access in init.

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