是否有必要在@interface中声明ivars以匹配属性？ [英] Is it necessary to declare ivars in @interface to match properties?

问题描述

可能重复：

Objective-C 2.0中的属性和实例变量

我对这两个代码段感到困惑：

I'm confused by these two code segments:

首先：

//.h
@interface Student : NSObject {

}
    @property (nonautomic, copy) NSString *name;
    @property (nonautomic, retain) NSNumber *age;
@end

//.m
@implementation Student
    @synthesize name;
    @synthesize age;
@end

第二名：

//.h
@interface Student : NSObject {
    NSString *name;   // <<============ difference
    NSNumber *age;    // <<============ difference
}
    @property (nonautomic, copy) NSString *name;
    @property (nonautomic, retain) NSNumber *age;
@end

//.m
@implementation Student
    @synthesize name;
    @synthesize age;
@end

这两项都可以。那么是否有必要在 {} 中声明变量？

Both of these can work. So is it necessary to declare variables in the {}?

推荐答案

从现代运行时（x86_64和ARM6 ...和iOS模拟器）开始，您不再需要声明合成的ivars。在第一个例子中，@synthesize正在为你添加实例变量。

Starting with the modern runtime (x86_64 and ARM6...and iOS Simulator) you no longer need to declare synthesized ivars. In the first example @synthesize is adding the instance variable for you.

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