Inheritance, initialization, method, convenience builder

Inheritance Features

only single inheritance is allowed in OC .

The class of the parent class is called the root class, and the root class in OC is nsobject( ancestor ).

Inherited content: All instance variables and? methods.

If the subclass is not satisfied? The implementation of the parent class? Method can be overridden (overwrite)? Method of the parent class .

Inheritance has transitivity

Completion of initialization method

-(void) init

{

Send the INIT message to Super: Executes the Init method implemented in the parent class

self = [super init];

if (self)

{

Initialize settings

}

Returns the object that was initialized for completion

return self;

}

The above is called the specified initialization method

Specifies that the initialization method has more than one other initialization method with multiple

Convenience Builder (+ method)

Returns an instance of this type, with the method name beginning with the class name.

Internal implementation: Encapsulates the Alloc and initialization methods. It's more concise.

1. Declaration and implementation of the convenience builder

+ (person *) Personwithname: (nssting *) name

{

Person *p = [[Person alloc] initwithname:name]

return p;

}

2. Create objects using the convenience builder

Person *p = [Person personwithname:@ "ianhao.cn"];

Inheritance, initialization, method, convenience builder