@synthesized 属性和 KVC
使用 @synthesize 生成的 setter 是否应该兼容 KVC？我发现生成的 getter 和 setter 符合 KVC 标准，它不应该调用其中一种方法吗？
@interface testing : NSObject
@property (nonatomic, retain) NSString *phone;
@end
实施：
@implementation testing
@synthesize phone;
- (id)init {
self = [super init];
return self;
}
// none of these is called with dot syntax, or setter setPhone
- (void)setValue:(id)value forKey:(NSString *)key
{
NSLog(@"%@",key);
[super setValue:value forKey:key];
}
-(void)setValue:(id)value forKeyPath:(NSString *)keyPath
{
NSLog(@"%@",keyPath);
[super setValue:value forKeyPath:keyPath];
}
@end
并用以下方法测试它：
testing *t = [[testing alloc] init];
[t setPhone:@"55555555"];
Should setter generated with @synthesize be KVC compilant or not? I found statement that getters and setters generated are KVC-compliant, shouldn't it call one of this methods?
@interface testing : NSObject
@property (nonatomic, retain) NSString *phone;
@end
implementation:
@implementation testing
@synthesize phone;
- (id)init {
self = [super init];
return self;
}
// none of these is called with dot syntax, or setter setPhone
- (void)setValue:(id)value forKey:(NSString *)key
{
NSLog(@"%@",key);
[super setValue:value forKey:key];
}
-(void)setValue:(id)value forKeyPath:(NSString *)keyPath
{
NSLog(@"%@",keyPath);
[super setValue:value forKeyPath:keyPath];
}
@end
and test it with:
testing *t = [[testing alloc] init];
[t setPhone:@"55555555"];
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评论（3）
我认为你搞错了。符合 KVC 并不意味着访问器会调用
-setValue:forKey:符合 KVC 意味着调用-setValue:forKey:将调用访问器。扩展一下：符合 KVC 仅意味着“遵循命名约定”。为什么这很重要？我可以将我的访问器方法称为任何我喜欢的名称。对于属性“Foo”：
这很好。但是像 Bindings 这样的机制会尝试通过调用
-setValue:forKey:来设置 Foo，它将尝试做正确的事情并使用访问器方法（如果我们编写了一个 setter 方法，那是因为我们希望它会被使用，对吧？）。但除非我们将 setter 方法命名为标准-setFoo:，否则就无法找到它。因此
-weakSetFoo:是一个 setter 方法，但属性 Foo 不符合 KVC。如果我将 setter 名称更改为
-setFoo:属性 Foo 现在符合 KVC 标准。默认情况下，合成的访问器方法将被正确命名。
I think you've got it the wrong way round.. KVC compliant doesn't mean that an accessor will call
-setValue:forKey:Being KVC compliant means that calling-setValue:forKey:will call the accessor.Expanding a bit: KVC compliant only means 'follows naming conventions'. Why is this important? I can call my accessor methods anything i like. For a property 'Foo':
This is fine. But a mechanism like Bindings will try to set Foo by calling
-setValue:forKey:will try to do the right thing and use the accessor method (if we wrote a setter method, it's because we want it to be used, right?). But unless we named our setter method the standard-setFoo:there's no way it will be found.So
-weakSetFoo:is a setter method, but the property Foo isn't KVC compliant.If i change the setter name to
-setFoo:the property Foo is now KVC compliant.Synthesized accessor methods will by default be named correctly.
您不需要为 KVO 实现 setValueForKey: 。它是在框架内为您实现的。通过使您的属性符合 KVO（您已使用 @property 和 @synthesize 完成），一切都会“神奇”地工作
----- update
另外，您的测试代码不会测试 KVO。要测试它，请执行以下操作：
You don't need to implement setValueForKey: for KVO. It is implemented for you within the framework. By making your properties KVO compliant (which you have done using @property and @synthesize), everything just works 'magically'
----- update
Also, your testing code would not test KVO. To test it, do something like:
事实上恰恰相反。
它们是
setValue:forKey和getValueforKey，它们查找符合 KVC 的属性，而不是通过它们合成的属性。当您编写
@synthesize property时，编译器实际上只是填充- (type) property和- (void) setProperty: (type)value类型读取/设置相应实例变量的方法。It is actually the other way round.
These are
setValue:forKeyandgetValueforKeywhich look up the KVC-compliant properties, not properties synthesized through them.When you write
@synthesize propertythe compiler actually just stuffs- (type) propertyand- (void) setProperty: (type)valuekind of methods which read/set corresponding instance variable.