9.面向对象与函数

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面向对象与函数

• main.m

#import <Foundation/Foundation.h>
#import "People.h"

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // 调用方法使用 []
        People *p1 = [[People alloc] init];
        [p1 report];  // name:visitor age:18
        int res1 = [p1 showWithA:10];
        NSLog(@"res1=%d",res1);  // res1=10
        int res2 = [p1 showWithA:10 andB:20];
        NSLog(@"res2=%d",res2);  // res2=30
        
        People *p2 = [[People alloc] initWithName:@"Admin" andAge:30];
        [p2 report];  // name:Admin age:30
        return 0;
    }
}

• People.h

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN
@interface People : NSObject
/*
 -: 对象方法 使用对象名调用
 +: 类方法 使用类名调用
 
 (void) report - void: 函数返回值类型
 (int)a - (int): 参数类型  a: 参数名
 
 函数名 - 1.report: 2.say: 3.showWithA 4.showWithA: andB:
 */
- (void) report;
+ (void) say;
- (int) showWithA:(int)a;
- (int) showWithA:(int)a andB:(int)b;
// 初始化方法
- (instancetype) init;
// 自定义初始化方法
- (instancetype) initWithName:(NSString *)name andAge:(int)age;
@end

NS_ASSUME_NONNULL_END

• People.m

#import "People.h"

@implementation People
{
    NSString *_name;
    int _age;
}

- (void) report
{
    //NSLog(@"report");
    //_name = @"reporter";
    
    NSLog(@"name:%@ age:%d",_name,_age);
    // 对象方法中调用类方法
    //[People say];
}

+ (void) say
{
    // 加号方法(类方法)无法调用成员变量
    NSLog(@"say something");
    
    // 类方法中调用对象方法，需要实例化
    //[[People alloc] report];
}

- (int) showWithA:(int)a
{
    return a;
}

- (int) showWithA:(int)a andB:(int)b
{
    return a + b;
}

- (instancetype)init
{
    self = [super init];
    if (self) {
        _name = @"visitor";
        _age = 18;
    }
    return self;
}

- (instancetype) initWithName:(NSString *)name andAge:(int)age
{
    self = [super init];
    if (self) {
        _name = name;
        _age = age;
    }
    return self;
}
@end