通过“属性名称"访问属性之间的区别相对于"self.propertyname"在目标C? [英] difference between accessing a property via "propertyname" versus "self.propertyname" in objective-c?

问题描述

在Objective-C中通过"propertyname"访问属性与"self.propertyname"之间的关系是什么?你能回答答案吗?

What is the nce between accessing a property via "propertyname" versus "self.propertyname" in objective-c? Can you cover in the answer:

1. 什么是最佳做法?
2. 这两种方法如何影响内存管理(保留计数/一个人的内存管理职责)
3. 其他优势/劣势

该场景的假设可能基于以下内容:

The assumption for the scenario could be based on the following:

头文件

@interface AppointmentListController : UITableViewController {
    UIFont *uiFont;
}
@property (nonatomic, retain) UIFont *uiFont;

实施

- (void)viewDidLoad {
    [super viewDidLoad];  

    uiFont = [UIFont systemFontOfSize:14.0];
    //VERSUS
    self.uiFont = [UIFont systemFontOfSize:14.0];

谢谢

推荐答案

使用propertyname仅访问实例变量.您有责任对其内容进行自己的内存管理；没有为您执行保留或释放.

Using propertyname just accesses the instance variable. You're responsible for doing your own memory management on its contents; no retains or releases are performed for you.

使用self.propertyname通常使用访问器.如果您使用的是@synthesize，则生成的访问器将按照您在@property行中指定的方式处理内存管理(您给出的示例使用retain，因此将新值设置为self.propertyname时将执行保留). .您还可以编写自己的访问器方法，以根据需要进行管理.

Using self.propertyname generally uses an accessor. If you're using @synthesize, the generated accessors will handle memory management as specified in your @property line (the example you gave uses retain, so a retain will be performed on setting a new value to self.propertyname). You can also write your own accessor methods that do management as you like.

更完整的解释在

A fuller explanation is in the Memory Management Programming Guide. Best practices in this case are generally to use @property and @synthesize to handle your variables, then use the self.propertyname accessors to reduce the memory management burden on yourself. The guide also recommends you avoid implementing custom accessors (i.e. using @property without @synthesize).

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