Dark Horse programmer-protocol (protocol), dark horse-protocol

Dark Horse programmer-protocol (protocol), dark horse-protocol
------ Java training, Android training, iOS training, and. Net training. We look forward to communicating with you! -------

• Can be used to declare a lot of methods (member variables cannot be declared)
• As long as a class complies with this Protocol, it is equivalent to having all the method declarations in this Protocol.
• As long as the parent class complies with a certain protocol, it is equivalent to the sub-class also complies

// Define a protocol named MyProtocol. h @ protocol MyProtocol <NSObject> @ required // requires implementation. If you do not know what to do, a warning will be issued. If you do not write anything, the default value is @ required-(void) test;-(void) test2; @ optional // not required-(void) test3; @ end Person. h @ protocol MyProtocol; // pre-statement of the protocol, similar to @ class @ interface Person: NSObject <MyProtocol> @ end Person. m # import MyProtocol. h; @ implementation Person-(void) test {}- (void) test2 {}@ end

• One protocol can comply with multiple other protocols. Multiple protocols are separated by commas (,).
• An agreement that complies with other protocols is equivalent to having a method statement in other Protocols

@ Protocol name <protocol 1, protocol 2>

@ End

1. Class Compliance Agreement: @ interface Class Name: parent class name <protocol name 1, protocol name 2> @ end2 protocol Compliance Agreement: @ protocol name <other protocol name 1, other protocol name 2> @ end1.

• NSObject is a base class, the most fundamental and basic class. Any other class will eventually inherit it.
• In fact, there is also a protocol named NSObject, which is a base protocol and the most fundamental and basic protocol.
• The NSObject Protocol declares many basic methods, such as description, retain, and release.
• We recommend that each new protocol comply with the NSObject protocol.

The object stored in obj3 must comply with the MyProtocol protocol; NSObject <MyProtocol> * obj3; id <MyProtocol> obj3; obj4 is required, and the saved object must comply with MyProtocol3, and inherits the attributes declared in the PersonPerson <MyProtocol3> * obj4; @ property can also be used as a protocol-compliant constraint @ property (nonatomic, strong) class Name <protocol name> * attribute name; @ property (nonatomic, strong) id <protocol name> attribute name; Protocol can be defined separately. in the H file, it can also be defined in a class. 1. If this Protocol is only used in a class, the protocol should be defined in this class. 2. If this protocol is used in many classes, the classification should be defined in a separate file and can be defined separately. h and. the m file can also be defined in the original Class 1. Generally, it is defined in a separate file 2 and defined in the original class category, only the syntax # import "TicketDelegate. h "@ interface Person: NSObject-(void) buyTicket; // has a proxy attribute. The proxy class name must comply with the TicketDeltegate Protocol @ property (nonatomic, retain) id <TicketDelegate> delegate; @ end