ios developer tiny share-20160805

今天讲Objective-C的属性访问控制

Property Attributes Indicate Data Accessibility and Storage Considerations

The examples shown so far all declare properties that are intended for complete public access. This means that other objects can both read and change the values of the properties.
In some cases, you might decide to declare that a property is not intended to be changed. In the real world, a person must fill out a large amount of paperwork to change their documented first or last name. If you were writing an official record-keeping app, you might choose that the public properties for a person’s name be specified as read-only, requiring that any changes be requested through an intermediary object responsible for validating the request and approving or denying it.
Objective-C property declarations can include property attributes, which are used to indicate, among other things, whether a property is intended to be read-only. In an official record-keeping app, the Person class interface might look like this:

@interface Person : NSObject
@property (readonly) NSString *firstName;
@property (readonly) NSString *lastName;
@end

Property attributes are specified inside parentheses after the @property keyword, and are described fully in Declare Public Properties for Exposed Data.