Objective-c语言_便利初始化函数和便利构造器

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便利初始化函数和便利构造器

mian.m

#import <Foundation/Foundation.h>#import "Teacher.h"int main(int argc, const char * argv[]) {    @autoreleasepool {        Teacher *teacher = [[Teacher alloc]init];                [teacher sayWord];                Teacher *teacher1 = [[Teacher alloc]init];        [teacher1 sayWord];                Teacher *teacher2 = [[Teacher alloc]initWithName:@"zengxinsheng" andAge:18];        [teacher2 sayWord];                Teacher *teacher3 = [Teacher teacherWithName:@"xuyu" andAge:18];        [teacher3 sayWord];                    }    return 0;}

Teacher.h

#import <Foundation/Foundation.h>@interface Teacher : NSObject{    NSString *_name ;    NSInteger _age ;}-(void)sayWord ;//便利初始化函数//注意命名规范: init开头-(id)initWithName:(NSString *)name           andAge:(NSInteger)age;/* 便利构造器(类方法) 便利构造器只不过是把对象分配内存 和 便利初始化函数 初始化对象的代码封装起来，让用户使用起来更加方便 注意命名规范:className 开头，例如teacher */+(id)teacherWithName:(NSString *)name              andAge:(NSInteger)age ;

Teacher.m

#import "Teacher.h"@implementation Teacher/* id:返回的类型是id数据类型，它是动态数据类型，它可以指向任何的对象，而不关心具体类型，在运行时检查其具体类型，可以对其发送任何(存在的)消息  self :指向当前对象的指针  super :指向父类对象的指针，子类使用super发送消息时，实际上就是告诉子类调用父类的方法。如果父类没有定义该方法，则会继续在继承链上寻找，直到寻找到位置，如果找NSObject位置依然没有找到，就会报错  其中(self = [super init]),此处[super init]任然返回子类对象，此处的目的是为了初始化父类的实例变量，如果返回nil,表明父类没有alloc成功，即不能再alloc子类对象  */-(id)init{    if (self = [super init])    {        _name = @"Rick";        _age = 25;    }    return self;}-(id)initWithName:(NSString *)name andAge:(NSInteger)age{    if (self = [super init])    {        _name = name;        _age = age;    }    return self;}//便利构造器+(id)teacherWithName:(NSString *)name andAge:(NSInteger)age{    Teacher *teacher = [[Teacher alloc]initWithName:name andAge:age];    return teacher;}-(void)sayWord{    NSLog(@"Teacher who names %@,%ld years old, say hello guys",_name,_age);}@end

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