Question

我创建了类：

@interface KVOGame : NSObject

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

@end

另一个属性：

@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]);
}

它崩溃了，错误：

由于未捕获的异常'NSUnknownKeyException'而终止应用程序，原因：'[valueForUndefinedKey：]：此类不是密钥platform.platformVersion的密钥值编码兼容。'

我做错了什么？

更新：valueForKeyPath:而不是valueForKey也无效 - 无论如何都会崩溃。

Answer 1

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

我认为永远不会创建game.platform。这是零

KVC点密钥问题

1 个答案: