如何在不破坏代码的情况下修复方法的重复声明

Question

我正在尝试将 Google 登录 SDK 包含到我的 AppDelegate.m 文件中，但它会引发此错误。

好像我只能定义一个方法的实例。

// Facebook SDK
- (void)applicationDidBecomeActive:(UIApplication *)application {
  [FBSDKAppEvents activateApp];
}

- (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation {
  return [[FBSDKApplicationDelegate sharedInstance] application:application
                                                        openURL:url
                                              sourceApplication:sourceApplication
                                                     annotation:annotation];
}

- (BOOL)application:(UIApplication *)application openURL:(NSURL *)url
  sourceApplication:(NSString *)sourceApplication annotation:(id)annotation {

  return [RNGoogleSignin application:application openURL:url sourceApplication:sourceApplication annotation:annotation];
}

@end

Answer 1

我想答案可能很简单：

- (BOOL)application:(UIApplication *)application 
            openURL:(NSURL *)url 
  sourceApplication:(NSString *)sourceApplication 
         annotation:(id)annotation 
{
    if([[FBSDKApplicationDelegate sharedInstance] application:application
                                                      openURL:url
                                            sourceApplication:sourceApplication
                                                   annotation:annotation])
    {
        return YES;
    }

    return [RNGoogleSignin application:application 
                               openURL:url
                     sourceApplication:sourceApplication 
                            annotation:annotation];
}

如果您添加更多，则在任何代理处理 openURL 时返回 YES。顺序无关紧要。此外，此方法已被弃用（请改用-application:openURL:options:），因此如果您希望您的应用在未来的更改中继续存在，则需要避免使用-application:openURL:sourceApplication:annotation:。

UPD：如果您“现在就想要”，请使用我的解决方案，gaussblurinc 的解决方案也有优点，所以如果您想要长期使用某些东西 - 肯定会从中获得一些东西。

Answer 2

@interface Services : NSObject<UIApplicationDelegate> // or ApplicationDelegateServices?

@property (strong, nonatomic, readonly) NSArray <id<UIApplicationDelegate>> *services;

@end

@interface Services()

@property (strong, nonatomic, readwrite) NSArray <id<UIApplicationDelegate>> *services;

@end
@class RNGoogleSignin;
@class FBSDKApplicationDelegate;
@implementation Services

- (void)setup {
    // put all items inside here
    //
    id<UIApplicationDelegate> googleApplicationDelegate = (<UIApplicationDelegate>)[RNGoogleSignin class];
    id<UIApplicationDelegate> facebookApplicationDelegate = (<UIApplicationDelegate>)[FBSDKApplicationDelegate sharedInstance];
    self.services = @[facebookApplicationDelegate, googleApplicationDelegate];

}
// services - create chain of responsibility for openURL scheme
// they only need to adopt to protocol canOpenURL and openURL
// each service is <UIApplicationDelegate>
- (NSArray <id<UIApplicationDelegate>>*) chainForSelector:(SEL)selector {
    return [self.services filteredArrayUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(id<UIApplicationDelegate>  _Nonnull evaluatedObject, NSDictionary<NSString *,id> * _Nullable bindings) {
        return [evaluatedObject respondsToSelector:selector];
    }]];
}

- (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation {
    // find all that responds to selector
    // filteredArrayUsingPredicate
    NSArray *chain = [self chainForSelector:_cmd];
    // or put your custom logic here, because all items in delegate are good enough to perform selector
    for (id<UIApplicationDelegate> delegate in chain) {
        if([delegate application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation]) {
            return YES;
        }
    }
    return NO;
}

@end

@interface AppDelegate<UIApplicationDelegate>

@property (nonatomic, weak) id<UIApplicationDelegate> services;

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation {
    // check that services responds to delegate method
    // if ([services respondsToSelector:...])
    if ([self.services respondsToSelector:_cmd]) {
        return [self.services application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation];
    }

    return NO/YES; // your choice
}

@end

毕竟

您可以将所有 AppDelegate 方法委托给外部类。

您的问题是“广泛使用 appDelegate 方法”。

似乎没有人愿意清理应用程序中的应用程序委托，因为“它可以正常工作”。我只是向您展示（是好是坏？不知道）责任链模式和简单委托的示例。

请记住，您可以将大部分 AppDelegate 方法委托给其他对象/类，例如，您可以提供智能的“PushNotificationsRouter”来处理所有与推送通知相关的方法。