使用Objection时,自定义协议的实现与无法识别的选择器崩溃

Question

我正在定义一个自定义协议:

@protocol NGSAuthProvider <NSObject>
- (BOOL)isReady;
- (BOOL)isSessionValid;
- (void)login;
- (void)logout;
- (NSString *)accessToken;
- (BOOL)handleOpenURL:(NSURL *)url;
@end

我想拥有不同的提供商.所以一个是Facebook提供商:

@interface NGSFacebookAuthProvider : NSObject <NGSAuthProvider>
@end

@interface NGSFacebookAuthProvider () <FBSessionDelegate>
@property BOOL ready;
@property(nonatomic, retain) Facebook *facebook;
@property(nonatomic, retain) NSArray *permissions;
@end

@implementation NGSFacebookAuthProvider
//Implementation of fbLogin, fbLogout and the methods in NGSAuthProvider that forward calls to self.facebook
- (NSString *)accessToken
{
  return [self.facebook accessToken];
}

@end

我设置了Objection从我的类绑定到协议.

@interface NGSObjectionModule : ObjectionModule
@end

@implementation NGSObjectionModule

- (void)configure 
{
   self bind:[NGSFacebookAuthProvider class] toProtocol:@protocol(NGSAuthProvider)];
}
@end

我设置了Global Injector:

@implementation NGSAppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
  ObjectionModule *module = [[NGSObjectionModule alloc] init];
  ObjectionInjector *injector = [Objection createInjector:module];
  [module release];

  [Objection setGlobalInjector:injector];
}

我在我的RootViewController中使用这个,如下所示:

@interface RootViewController : UITableViewController
@end

@interface RootViewController ()
@property(nonatomic, retain) id<NGSAuthProvider> authProvider;
@end

@implementation RootViewController
- (void)viewDidLoad {
  [super viewDidLoad];
  self.authProvider = [[Objection globalInjector] getObject:@protocol(NGSAuthProvider)];
}

- (void)processConfig {
  NSString *token = [self.authProvider accessToken];
  // use the access token
}
@end

当我运行它时,我收到以下错误:

2011-07-26 21:46:10.544 ngs[6133:b603] +[NGSFacebookAuthProvider accessToken]: unrecognized selector sent to class 0x30c7c
2011-07-26 21:46:10.546 ngs[6133:b603] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[NGSFacebookAuthProvider accessToken]: unrecognized selector sent to class 0x30c7c'
*** Call stack at first throw:
(
    0   CoreFoundation                      0x00e825a9 __exceptionPreprocess + 185
    1   libobjc.A.dylib                     0x00fd6313 objc_exception_throw + 44
    2   CoreFoundation                      0x00e8417b +[NSObject(NSObject) doesNotRecognizeSelector:] + 187
    3   CoreFoundation                      0x00df3966 ___forwarding___ + 966
    4   CoreFoundation                      0x00df3522 _CF_forwarding_prep_0 + 50
    5   ngs                                 0x0000324b -[RootViewController processConfig] + 731
    6   ngs                                 0x000041a2 __33-[RootViewController viewDidLoad]_block_invoke_0 + 50

所以我的类实现了协议.它已成功分配给id<NGSAuthProvider>.我尝试[[NGSFacebookAuthProvider alloc] init]明确地构造而不是使用Objection,它仍然崩溃了.

我尝试使用objc/runtime.h方法循环遍历选择器,以查看哪些选择器存在,但它唯一发现的是initialize:

- (void)logSelectors:(id)obj
{
    int i=0;
    unsigned int mc = 0;
    Method * mlist = class_copyMethodList(object_getClass([obj class]), &mc);
    NSLog(@"%d methods", mc);
    for(i=0;i<mc;i++)
        NSLog(@"Method no #%d: %s", i, sel_getName(method_getName(mlist[i])));

    free(mlist);
}

这必须是我想念的简单事情.我使用Cocoa定义的协议,没有这个问题.我已经为UIViewController基于代理的代理定义了自定义协议而没有问题.

我很难过为什么Obj-C运行时找不到我的方法!如果我改变id<NGSAuthProvider>来NGSFacebookAuthProvider构建它明确地那么它所有的作品.

解:

问题是我误解了如何绑定到协议.一种有效的方法是:

@implementation NGSObjectionModule

- (void)configure 
{
  [self bind:[[[NGSFacebookAuthProvider alloc] init] autorelease] toProtocol:@protocol(NGSAuthProvider)];
}
@end

我想要做的是将类绑定到协议,但Objection可能不知道要调用的初始化器？

Answer 1

问题是你试图使用静态类方法（表示因为你有一个+）而不是在你的对象实例上运行的方法（这就是你写的，带有 - ）