ios - KVC 点键问题

Question

我创建类:

@interface KVOGame : NSObject

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

@end

还有一个是它的属性:

@interface KVOPlatform : NSObject

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

@end

然后我尝试使用 KVC 来获取这样的“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:

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[ valueForUndefinedKey:]: this class is not key value coding-compliant for the key platform.platformVersion.'

我做错了什么？

更新:valueForKeyPath: 而不是 valueForKey 也不起作用 - 无论如何都会崩溃。

Answer 1

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

我假设 game.platform 永远不会被创建。为零