KVC点键问题

Question

我创造了一个课程：

@interface KVOGame : NSObject

@property (nonatomic, strong) NSString *name;
@property (nonatomic, strong) NSString *releaseDate;
@property (nonatomic, strong) KVOPlatform *platform;

@end

还有另一个用来买它的：

@interface KVOPlatform : NSObject

@property (nonatomic, strong) NSString *platformName;
@property (nonatomic, strong) NSString *platformVersion;

@end

然后我试着用KVC来获得像这样的"platformVersion“

@interface KVOViewController ()

@end

@implementation KVOViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    KVOGame *game = [[KVOGame alloc] init];
    game.name = @"Bayonetta";
    game.releaseDate = @"8.10.2009";
    game.platform.platformName = @"PS3, Xbox360";
    game.platform.platformVersion = @"all versions";

    NSString *identifier = @"platform.platformVersion";

    NSLog(@"%@", [game valueForKey:identifier]);
}

它因错误而崩溃：

终止应用程序的原因是：“valueForUndefinedKey:这个类不符合键platform.platformVersion的键值编码。”

我做错了什么？

更新：valueForKeyPath:而不是valueForKey也不起作用。

Answer 1

试试NSLog(@"%@", [game valueForKeyPath:identifier]);

我认为game.platform永远不会被创建。是零