kvc机制与kvc的常用方法

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kvc是key value coding的缩写，即：键值编码。键值编码提供了非常强大的功能：只要存在访问器方法、声明属性或实例变量，就可以将其名字指定为字符串来访问。

// 返回表示属性的键字符串对应的值

- (id)valueForKey:(NSString *)key;

Person *p1 = [[Person alloc] init];[p1 setValue:@"张三" forKey:@"name"]; NSString *name = [p1 valueForKey:@"name"];

// 将键字符串key所对应的属性的值设置为value

- (void)setValue:(id)value forKey:(NSString *)key;

// p1是Person类的对象，name是Person类的一个属性Person *p1 = [[Person alloc] init];       [p1 setValue:@"张三" forKey:@"name"];

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// 以点“.”切分键路径，并使用第一个键像接收器发送valueForKey：方法，然后在使用路径的下一个键，向得到的对象发送valueForKey：fangfa，如此反复操作，返回最后获得的对象。

- (id)valueForKeyPath:(NSString *)keyPath;

// 与valueForKeyPath:方法同样取出对象，这里只对路径中的最后一个键调用setValue：ForKey：方法，并设置属性值为value。

- (void)setValue:(id)value forKeyPath:(NSString *)keyPath;

例:

Dog类：

@interface <span style="color:#cc0000;">Dog</span> : NSObject// 狗的品种@property (nonatomic, copy) NSString *name;@end

Person类：

#import <Foundation/Foundation.h>#import "Dog.h"@interface <span style="color:#cc0000;">Person</span> : NSObject// 姓名@property (nonatomic, copy) NSString *name;// 年龄@property (nonatomic, assign) int age;// 电子邮件@property (nonatomic, copy) NSString *email;@property (nonatomic, strong) Dog *dog;@end

main函数：

#import <Foundation/Foundation.h>#import "Person.h"int main(int argc, const char * argv[]) {    @autoreleasepool {   Person *p1 = [[Person alloc] init];   // @"dog.name" 这个就叫做keyPath 或者叫 "属性的路径"   [p1 setValue:@"哈士猫" forKeyPath:@"dog.name"];

<p style="margin-top: 0px; margin-bottom: 0px; font-size: 14px; line-height: normal; font-family: Menlo; color: rgb(52, 149, 175);"><span style="font-variant-ligatures: no-common-ligatures; color: #000000"> </span>NSString<span style="font-variant-ligatures: no-common-ligatures; color: #000000"> *dogName = [p1 </span>valueForKeyPath<span style="font-variant-ligatures: no-common-ligatures; color: #000000">:</span><span style="font-variant-ligatures: no-common-ligatures; color: #b4261a">@"dog.name"</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000">];</span></p>

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// 根据字典的键，找对应的属性，为属性赋值（字典转模型）

- (void)setValuesForKeysWithDictionary:(NSDictionary *)keyedValues;

#import <Foundation/Foundation.h>#import "Person.h"int main(int argc, const char * argv[]) {    @autoreleasepool {   Person *p1 = [[Person alloc] init];  NSDictionary *bz = @{                             @"name" : @"小明",                             @"age" : @28,                             @"email" : @"rzc0714@163.com",                             @"dog" : @{@"name" : @"加肥猫"}                             };           [p1 setValuesForKeysWithDictionary:bz];

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// 把对象转成字典

- (NSDictionary *)dictionaryWithValuesForKeys:(NSArray *)keys;

   // 把对象转成字典        NSDictionary *dict = [p1 dictionaryWithValuesForKeys:@[@"name", @"age", @"email", @"dog"]];

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