Obj-C @synthesize [英] Obj-C @synthesize

问题描述

可能重复：

在Objective C中使用下划线前缀属性名称

iPhone App Developer初学者：

iPhone App Developer Beginner here:

in .h

@property (nonatomic, retain) IBOutlet UILabel *detailDescriptionLabel;

in .m

@synthesize detailDescriptionLabel = _detailDescriptionLabel;

我习惯看到

@synthesize detailDescriptionLabel;

= _ 让我失望，这是做什么的？

the = _ is throwing me off, what is this doing?

推荐答案

每个属性都有一个实例变量支持。该语言允许以不同的方式命名它们。通过 @synthesize detailDescriptionLabel = _detailDescriptionLabel; ，您基本上是说使用 _detailDescriptionLabel 作为后备实例变量property detailDescriptionLabel 。如果您只是执行 @synthesize detailDescriptionLabel; ，它会隐含地理解实例变量具有相同的名称。

Each property is backed by an instance variable. The language allows for them to be named differently. By doing @synthesize detailDescriptionLabel = _detailDescriptionLabel;, you're basically saying that use _detailDescriptionLabel as the backing instance variable for the property detailDescriptionLabel. If you just do @synthesize detailDescriptionLabel;, it implicitly understands that the instance variable has the same name.

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