KVC的使用(对一个对象的成员变量进行操作(赋值/取值))

#import "MainViewController.h"
#import "Student.h"
@interface MainViewController ()
@end
@implementation MainViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
self.view.backgroundColor = [UIColor cyanColor];

//KVC的使用

Student *stu = [[Student alloc] init];

//KVC的作用:对一个对象的成员变量进行操作(赋值/取值)

//赋值的方法
[stu setValue:@"adfasdf" forKey:@"name"];
//    [stu setValue:@"米4像苹果1" forKey:@"Name"];  //第一个查找
//     [stu setValue:@"米4像苹果2" forKey:@"_Name"];   //找不到
//    [stu setValue:@"米4像苹果3" forKey:@"_name"];  //

//这个是一个类中的属性赋值
//    stu setValue:<#(id)#> forKeyPath:<#(NSString *)#>

NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:@"222", @"StudentID", @"liuyafang", @"name" ,nil];

[stu setValuesForKeysWithDictionary:dic];

//取值的方法
NSLog(@"%@",[stu valueForKey:@"name"]);

//KVO  键值观察  (注册一个观察者)(自己监视自己对象的内容)

//参数1:观察谁
//参数2:观察哪个属性
//参数3:在实现方法中获得新值合适旧值
//参数4:任意的指针类型
[stu addObserver:self forKeyPath:@"name" options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOld context:@"aaa"];

stu.name = @"pingguo45";

}
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
NSLog(@"%@",keyPath);
NSLog(@"%@",object);
NSLog(@"%@",change);
NSLog(@"%@",context);
}
- (void)dealloc
{
//    self removeObserver:<#(NSObject *)#> forKeyPath:<#(NSString *)#>
[super dealloc];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
/*
#pragma mark - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.
}
*/
@end

#import <Foundation/Foundation.h>
@interface Student : NSObject
@property (nonatomic , retain)NSString *name;
@property (nonatomic , retain)NSString *sex;
@property (nonatomic , retain)NSString *studengID;
//利用kvc对model进行封装
- (instancetype) initWihtDictionary:(NSDictionary *)dic;
@end

#import "Student.h"
@implementation Student
- (void)setValue:(id)value forUndefinedKey:(NSString *)key
{
//这个方法在类的内部实现,就用就是纠错
//一旦在赋值过程中,发现key没有周到对应的成员变量,就会调用这个发放
//如果没有重写个方法,就会crash

if ([key isEqualToString:@"id"]) {
_studengID = value;
}
}
- (id)valueForUndefinedKey:(NSString *)key
{
//取值的纠错方法
if ([key isEqualToString:@"id"]) {
return  self.superclass;
}

return nil;
}
- (instancetype) initWihtDictionary:(NSDictionary *)dic
{
self = [super init];
if (self) {
[self setValuesForKeysWithDictionary:dic];
}
return self;
}
- (void)dealloc
{
[_name release];
[_sex release];
[super dealloc];
}
@end