iOS KVC(Key-Value Coding)

╰半夏微凉° 2021-09-17 13:02 284阅读 0赞

##### 常见用法： #####

*  获取值  
    
    
     *  valueForKey: 依据属性名取值
     *  valueForKeyPath: 依据路径取值(如：*\[person valueForKeyPath:@”car.price”\]*)
     *  valueForUndefinedKey 默认实现是抛出异常。能够重写这个函数做错误处理 ( 比較少用 )
 *  改动值  
    
    
     *  setValue:forKey: 依据属性设值
     *  setValue:forKeyPath: 依据路径设值
     *  setValue:forUndefinedKey:
     *  setNilValueForKey: 当对非类对象属性设置nil时。调用。默认抛出异常
 *  字典转模型  
    
    
     *  setValuesForKeysWithDictionary: 字典转模型

##### 上代码： #####

定义一个HSCar类

//
    // HSCar.h
    // KVC
    //
    // Created by hans on 15/7/13.
    // Copyright © 2015年 hans. All rights reserved.
    //
    
    #import <Foundation/Foundation.h>
    
    @interface HSCar : NSObject
    
    /** 名字 */
    @property (nonatomic, copy) NSString *name;
    
    /** 价格 */
    @property (nonatomic, assign) double price;
    
    @end

定义一个HSBook类

//
    // HSBook.h
    // KVC
    //
    // Created by hans on 15/7/13.
    // Copyright © 2015年 hans. All rights reserved.
    //
    
    #import <Foundation/Foundation.h>
    
    @interface HSBook : NSObject
    /** 书名 */
    @property (nonatomic, copy) NSString *name;
    /** 价格 */
    @property (nonatomic, assign) double price;
    @end

定义一个HSPerson类

//
    // HSPerson.h
    // KVC
    //
    // Created by hans on 15/7/13.
    // Copyright © 2015年 hans. All rights reserved.
    //
    
    #import <Foundation/Foundation.h>
    @class HSCar;
    
    @interface HSPerson : NSObject
    
    /** 名字 */
    @property (nonatomic, copy) NSString *name;
    
    /** 年龄 */
    @property (nonatomic, copy) NSString *age;
    
    /** 车 */
    @property (nonatomic, strong) HSCar *car;
    
    @end

--------------------

//
    // HSPerson.m
    // KVC
    //
    // Created by hans on 15/7/13.
    // Copyright © 2015年 hans. All rights reserved.
    //
    
    #import "HSPerson.h"
    
    @implementation HSPerson
    {
        // 体重
        double _weight;
    }
    
    - (void)showWeight
    {
        NSLog(@"weight: %f", _weight);
    }
    
    @end

在ViewController实现

//
    // ViewController.m
    // KVC
    //
    // Created by hans on 15/7/13.
    // Copyright © 2015年 hans. All rights reserved.
    //
    
    #import "ViewController.h"
    #import "HSPerson.h"
    #import "HSCar.h"
    #import "HSBook.h"
    
    @interface ViewController ()
    
    @end
    
    @implementation ViewController
    
    - (void)viewDidLoad {
        [super viewDidLoad];
    
    
        HSPerson *person = [HSPerson new];
        person.name = @"hans";
        person.age = 23;
    
        person.car = [HSCar new];
        person.car.name = @"兰博基尼";
        person.car.price = 10000000.0;
    
        /** valueForKey: */
        NSLog(@"name: %@ age: %@", [person valueForKey:@"name"], [person valueForKey:@"age"]);
        // 2015-07-13 22:32:02.356 KVC[54356:872650] name: hans age: 23
    
        /** valueForKeyPath: */
        NSLog(@"name：%@ price： %@", [person valueForKeyPath:@"car.name"], [person valueForKeyPath:@"car.price"]);
        // 2015-07-13 22:51:27.075 KVC[54669:885579] name：兰博基尼 price： 10000000
    
    
        /** setValue:forKey: */
        [person setValue:@"hanshhh" forKey:@"name"];
        [person setValue:@"100" forKey:@"age"];
        NSLog(@"name: %@ age: %@", [person valueForKey:@"name"], [person valueForKey:@"age"]);
        // 2015-07-13 22:53:54.876 KVC[54709:886954] name: hanshhh age: 100
    
        /** setValue:forKeyPath: */
        [person setValue:@"法拉利" forKeyPath:@"car.name"];
        [person setValue:@(9999999) forKeyPath:@"car.price"];
        NSLog(@"name：%@ price： %@", [person valueForKeyPath:@"car.name"], [person valueForKeyPath:@"car.price"]);
        // 2015-07-13 22:56:36.336 KVC[54767:888926] name：法拉利 price： 9999999
    
        /** 更改私有属性 */
        [person setValue:@(120) forKeyPath:@"_weight"];
        [person showWeight];
        // 2015-07-13 23:01:15.151 KVC[54847:892122] weight: 120.000000
    
        /** 字典转模型 */
        // 1.简单转换
        NSDictionary *dict1 = @{
                               @"name"  : @"汉斯",
                               @"age" : @"23",
                               };
    
        [person setValuesForKeysWithDictionary:dict1];
        NSLog(@"name : %@, age : %d", person.name, person.age);
        // 2015-07-13 23:04:20.298 KVC[54943:895092] name : 汉斯, age : 23
    
        // 2.复杂模型转换(注意：person.car不能转换。会变为字典对象，事实上就是简单的指针赋值而已)
        NSDictionary *dict2 = @{
                               @"name"  : @"汉斯哈哈哈",
                               @"age" : @"23",
                               @"car" : @{
                                       @"name" : @"兰博基尼",
                                       @"price" : @"10000000"
                                       },
                                };
        [person setValuesForKeysWithDictionary:dict2];
        NSLog(@"%@", person.car);
    // 2015-07-13 23:10:32.310 KVC[55019:899474] { 
    // name = "\U5170\U535a\U57fa\U5c3c";
    // price = 10000000;
    // }
    
    
        /** 其它运算 */
        HSBook *book1 = [HSBook new];
        book1.name = @"结网";
        book1.price = 51.0;
    
        HSBook *book2 = [HSBook new];
        book2.name = @"失控";
        book2.price = 40.0;
    
        HSBook *book3 = [HSBook new];
        book3.name = @"异类";
        book3.price = 60.0;
    
        person.books = @[book1, book2, book3];
    
        NSLog(@"%@", [person.books valueForKeyPath:@"@count"]);
        NSLog(@"%@", [person.books valueForKeyPath:@"@avg.price"]);
        NSLog(@"%@", [person.books valueForKeyPath:@"@min.price"]);
        NSLog(@"%@", [person.books valueForKeyPath:@"@max.price"]);
    
    // 2015-07-13 23:20:43.434 KVC[55171:905643] 3
    // 2015-07-13 23:20:43.434 KVC[55171:905643] 50.333333333333333333333333333333333333
    // 2015-07-13 23:20:43.435 KVC[55171:905643] 40
    // 2015-07-13 23:20:43.435 KVC[55171:905643] 60
    }
    
    - (void)didReceiveMemoryWarning {
        [super didReceiveMemoryWarning];
        // Dispose of any resources that can be recreated.
    }
    
    @end