iOS KVC KVO 代码 详解

//
//  ViewController.m
//  test_kvo_kvc_01
//
//  Created by admin on 4/7/16.
//  Copyright © 2016 jeffasd. All rights reserved.
//

#import "ViewController.h"
#import "Persion.h"
//#import <obj/runtime>

static NSString * const TESTSTRING = @"123";

#define KVOSTRING   @"321"

@interface ViewController ()

@property (nonatomic, strong, readonly) NSString *viewName;

@property (nonatomic, strong, readonly) Persion *xiaozhan;

@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];

[self testForKVO];
}

- (void)testForKVO{

_xiaozhan = [Persion new];

[_xiaozhan addObserver:self forKeyPath:@"personName" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:KVOSTRING ];

}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context{

NSLog(@"the context is %@", context);

if (context == KVOSTRING) {
NSLog(@"kvo");
return;
}else{
[super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
}
}

- (void)removeObservation{
[_xiaozhan removeObserver:self forKeyPath:@"personName"];
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{

//    [_xiaozhan setValue:[NSNumber numberWithInt:12] forKey:@"age"];

//    _xiaozhan.age = 122;

_xiaozhan.personName = @"123";

//    [_xiaozhan setPersonName:@"xiaozhan"];

}

- (IBAction)buttonAction:(UIButton *)sender {

[self removeObservation];

}

- (void)testForKVC{
Persion *xiaoming = [Persion new];

//    [xiaoming setValue:@"xiaoming1" forKey:@"name"];

//    [xiaoming setValue:nil forKey:@"name"];

[xiaoming setValue:nil forKey:@"age"];

//    [xiaoming setValue:[NSNumber numberWithInt:12] forKey:@"name"];
//    [xiaoming setValue:[NSNumber numberWithInt:12] forKey:@"name1"];

//还有一个需要注意的是KVC 并没有类型检验，毕竟Object-C 还是动态的啦
NSLog(@"the name is %@", xiaoming.name);

NSLog(@"the class name is %@", [xiaoming.name class]);

//    ViewController *VC = [ViewController new];
//    [VC setValue:@"123" forKey:@"viewName"];
}

- (BOOL)validateValue:(inout id  _Nullable __autoreleasing *)ioValue forKey:(NSString *)inKey error:(out NSError * _Nullable __autoreleasing *)outError{

return NO;
}

- (nullable id)valueForUndefinedKey:(NSString *)key{

return @"123";
}

- (void)setNilValueForKey:(NSString *)key{

}

- (void)setValue:(nullable id)value forUndefinedKey:(NSString *)key{

//    NSLog(@"the value is %@", value);
//    NSLog(@"the key is %@", key);

}

- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

@end

//
//  Persion.h
//  test_kvo_kvc_01
//
//  Created by admin on 4/7/16.
//  Copyright © 2016 jeffasd. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Persion : NSObject

@property (nonatomic, strong, readonly) NSString *name;

@property (nonatomic, assign) NSUInteger age;

@property (nonatomic, strong) NSString *personName;

@end

//
//  Persion.m
//  test_kvo_kvc_01
//
//  Created by admin on 4/7/16.
//  Copyright © 2016 jeffasd. All rights reserved.
//

#import "Persion.h"

#define KVOSTRING   @"personName"

@interface Persion ()

@property (nonatomic, strong)NSString *identifier;

@end

@implementation Persion

//- (BOOL)validateName:(inout id  _Nullable __autoreleasing *)ioValue forKey:(NSString *)inKey error:(out NSError * _Nullable __autoreleasing *)outError{
//
//    NSLog(@"ioValue is %@", ioValue);
//
//    NSLog(@"inkey is %@", inKey);
//
//    return NO;
//}

- (BOOL)validateValue:(inout id  _Nullable __autoreleasing *)ioValue forKey:(NSString *)inKey error:(out NSError * _Nullable __autoreleasing *)outError{

return NO;
}

- (nullable id)valueForUndefinedKey:(NSString *)key{

return @"valueUndefinedKey";
}

- (void)setNilValueForKey:(NSString *)key{

NSLog(@"the key is %@", key);

}

- (void)setValue:(nullable id)value forUndefinedKey:(NSString *)key{

}

//- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context{
//
//    NSLog(@"the context is %@", context);
//
//    if (context == KVOSTRING) {
//        NSLog(@"kvo");
//    }else{
//        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
//    }
//}

@end