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KVC
KVC是KeyValueCoding的简称，它是一种可以直接通过字符串的名字(key)来访问类属性的机制。而不是通过调用Setter、Getter方法访问。
Person.h
@interface Person : NSObject
@property (strong, nonatomic) NSString *name;
@property (assign, nonatomic) NSInteger age;
@property (strong, nonatomic) NSString *code;
@property (assign, nonatomic) double height;
@end
main.m
NSDictionary *dic = @{@"name" : @"admin",
@"age" : @13, @"code" : @"111222333",
@"height" : @12.4};
Person *person = [[Person alloc] init];
person.name = @"person name";
//KVC
[person setValue:@"KVC name" forKey:@"name"];
[person setValue:@12 forKey:@"age"];
[person setValue:@"112233" forKey:@"code"];
[person setValue:@15.9 forKey:@"height"];
// 利用KVC将json转Model
for (NSString *key in dic) {
[person setValue:dic[key] forKey:key];
}
// 一次性转
[person setValuesForKeysWithDictionary:dic];
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KVO
KVO,即：Key-Value Observing，它提供一种机制，当指定的对象的属性被修改后，则对象就会接受到通知。简单的说就是每次指定的被观察的对象的属性被修改后，KVO就会自动通知相应的观察者了。
设置监听者
- (void)setStock:(Stock *)stock {
_stock = stock;
// 1. 设置监听(注册监听)
// 参数：监听者，监听值，监听选项，上下文
[_stock addObserver:self forKeyPath:@"price" options:NSKeyValueObservingOptionNew context:nil];
}
处理监听
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
NSLog(@"keypath : %@", keyPath);
NSLog(@"object : %@", object);
NSLog(@"change : %@", change);
// 2. 处理监听（当股票涨到40以上后，调用sell方法卖出）
NSNumber *newPriceNumber = change[@"new"];
if ([newPriceNumber intValue] >= 40) {
[self sell];
}
}
change字典与添加观察者中的参数相对应
NSKeyValueObservingOptions change
-------------------------------------------
NSKeyValueObservingOptionNew @{kind = ;new = ;}
NSKeyValueObservingOptionOld @{kind = ;old = ;}
NSKeyValueObservingOptionInitial @{kind = ;}
NSKeyValueObservingOptionPrior @{kind = 1;
notificationIsPrior = 1;} @{kind = 1;} @{kind = 1;notificationIsPrior = 1;}
移除监听
- (void)dealloc {
// 3. 移除监听
[_stock removeObserver:self forKeyPath:@"price"];
}
