类
定义和C++一样，都需要类的声明和实现，而且头文件进行类声明，.m文件类的实现。
类在@interface和@end之间声明成员变量和方法，在@implementation和@end之间实现方法；
Person.h
@interface Person : NSObject <Action>
{
// 在大括号内定义成员变量
// 定义成员变量，默认是@protect
NSString* name;
NSInteger age;
// 成员变量访问控制
@private
NSString* private_member;
@protected
NSString* protected_member;
@public
NSString* public_member;
}
// 定义属性配对在.m文件里面定义@synthesize
// @property语义：
// nonatomic/atomic
// readonly/readwrite
// assign/week 简单赋值，弱引用
// retain/strong释放旧对象，retain，强引用
// copy 复制新对象
@property(nonatomic, retain) NSString* name;
@property(nonatomic) NSInteger age;
// 以－号开头
// 定义对象方法，初始化方法以initWithXXXX开始
-(id)initWithName:(NSString*)n andAge: (NSInteger)a;
-(void)print;
// 类方法,创建默认对象；以＋开头
+(Person*)createPerson;
+(int)createCount;
@end
Person.m
@implementation Person
@synthesize name;
@synthesize age;
// 静态变量
static int count = 0;
// 常量
const int MAX_COUNT = 30;
-(id)initWithName:(NSString *)n andAge:(NSInteger)a{
// super指向父类
self = [super init];
if (self) {
name = n;
age = a;
}
++count;
return self;
}
-(void)print{
NSLog(@"Person: name=%@, age=%ld", name, age);
}
// 类方法,创建默认对象；以＋开头
+(Person *)createPerson{
return [[Person alloc] initWithName:@"default" andAge:0];
}
+(int)createCount{
return count;
}
//做一个标记，以下是实现Action协议
#pragma mark With Action Protocol
-(void)walk{
NSLog(@"Person %@ walk!", name);
}
-(void)smile{
NSLog(@"Person %@ smile", name);
[self privateMethod];
}
// 定义私有方法，不再头文件中声明;子类无法访问
-(void)privateMethod{
NSLog(@"This is privateMethod");
}
@end
main.m
#import <Foundation/Foundation.h>
#import "Person.h"
#import "Employee.h"
#import "PersonSub.h"
int main(int argc, const char * argv[]) {
@autoreleasepool {
/*
Person *p = [Person alloc]; // 申请空间
p = [p initWithName:@"xuzhiming" andAge:33]; // 调用初始化
[p release]; // 释放空间
*/
// xCode 现在采用ARC，就不需要手动调用release了
Person *p = [[Person alloc] initWithName:@"xuzhiming" andAge:33];
// 方法调用
[p print];
// 调用分类的方法
[p newPrint];
// 属性调用
NSLog(@"p.name=%@, p.age=%ld", p.name, p.age);
// 公共成员变量调用
p->public_member = @"public_member";
NSLog(@"public_member = %@", p->public_member);
// 判断Person是否实现了Action协议
if ([p conformsToProtocol:@protocol(Action)]) {
NSLog(@"Person 遵循 Action协议");
[p walk];
[p smile];
}
// 判断Person是否实现了run方法
if ([p respondsToSelector:@selector(run)]) {
[p run];
}
else{
NSLog(@"p没有run方法");
}
// 类方法调用
Person *p2 = [Person createPerson];
[p2 print];
Employee *e = [[Employee alloc] initWithName:@"longma" andAge:30 andEducation:@"本科"];
// Employee的print覆盖了父类的方法，只需要定义一样的方法即可
[e print];
}
return 0;
}
输出结果：
2016-03-10 01:51:22.450 MyOCLearn[2164:74204] Person: name=xuzhiming, age=33
2016-03-10 01:51:22.452 MyOCLearn[2164:74204] Person newPrint name = xuzhiming
2016-03-10 01:51:22.452 MyOCLearn[2164:74204] p.name=xuzhiming, p.age=33
2016-03-10 01:51:22.452 MyOCLearn[2164:74204] public_member = public_member
2016-03-10 01:51:22.452 MyOCLearn[2164:74204] Person 遵循 Action协议
2016-03-10 01:51:22.452 MyOCLearn[2164:74204] Person xuzhiming walk!
2016-03-10 01:51:22.452 MyOCLearn[2164:74204] Person xuzhiming smile
2016-03-10 01:51:22.453 MyOCLearn[2164:74204] p没有run方法
2016-03-10 01:51:22.453 MyOCLearn[2164:74204] Person: name=default, age=0
2016-03-10 01:51:22.453 MyOCLearn[2164:74204] Employee name=longma, age=30, education=本科
2016-03-10 01:51:22.454 MyOCLearn[2164:74204] Employee name=longma, age=30, education=本科
Program ended with exit code: 0
