关于Sign In with Apple的介绍就不讲了，直接进入正题吧！

一、苹果开发者网站的配置

Certificates,IDs & Profiels->Keys->+号

1585892549402.jpg

点击Configure，选择Primary App ID（主应用程序ID，如果你这个账号有多个App的话，都可以用这一个Key），然后点Save。最后一步会有一个私钥(.p8的文件)，只能下载一次，所以要保存好。如果丢了只能重新创建一个Key了。这个文件的是后面服务器跟Apple做验证的时候用来加密的，下面会讲到。

开发者中心配置1.jpg

二、Xcode配置和代码

WX20200403-140155@2x.png

选择Sign in with Apple完，在下面的列表就有了。
添加AuthenticationServices.framework

1585896018396.jpg

导入系统头文件#import <AuthenticationServices/AuthenticationServices.h>

//typedef void (^YDSignInAppleCompletion) (NSString * __nullable errorText,NSString * __nullable appleUserID ,NSString * __nullable identityToken, NSString * __nullable name);
 (void)signInAppleCompletion:(YDSignInAppleCompletion)completion {
    if (@available(iOS 13.0, *)) {
        _completion = completion;
        ASAuthorizationAppleIDProvider *appleIDProvider = [[ASAuthorizationAppleIDProvider alloc] init];
        ASAuthorizationAppleIDRequest *appleIDRequest = [appleIDProvider createRequest];
        appleIDRequest.requestedScopes = @[ASAuthorizationScopeFullName, ASAuthorizationScopeEmail];
        ASAuthorizationController *controller = [[ASAuthorizationController alloc] initWithAuthorizationRequests:@[appleIDRequest]];
        controller.delegate = self;
        controller.presentationContextProvider = self;
        [controller performRequests];
    }
    else {
        if (completion) {
            completion(@"授权失败",nil,nil,nil);
        }
    }
}
#pragma mark - ASAuthorizationControllerDelegate
- (void)authorizationController:(ASAuthorizationController *)controller didCompleteWithAuthorization:(ASAuthorization *)authorization NS_SWIFT_NAME(authorizationController(controller:didCompleteWithAuthorization:))  API_AVAILABLE(ios(13.0)) {
    if ([authorization.credential isKindOfClass:[ASAuthorizationAppleIDCredential class]]) {
        ASAuthorizationAppleIDCredential *appleIDCredential = (ASAuthorizationAppleIDCredential *)authorization.credential;
        //Apple用户的唯一标识符，可以理解为微信等第三方的open_id
        NSString *user = appleIDCredential.user;
        //这三个字段只有第一次授权的时候有，后续再用苹果登录就会是空了，可在手机的设置《密码与安全性》删掉授权来测试看看
        NSString *familyName = appleIDCredential.fullName.familyName;
        NSString *givenName = appleIDCredential.fullName.givenName;
        NSString *email = appleIDCredential.email;
        //服务器验证使用的参数
        //identityToken是JWT格式的数据，解开的内容在下面的服务器验证会写
        NSString *identityToken = [[NSString alloc] initWithData:appleIDCredential.identityToken encoding:NSUTF8StringEncoding];
        //authorizationCode也是JWT格式的数据调用Apple验证接口(https://appleid.apple.com/auth/token)会用到
        NSString *authorizationCode = [[NSString alloc] initWithData:appleIDCredential.authorizationCode encoding:NSUTF8StringEncoding];
        NSLog(@"identityToken = %@",identityToken);
        NSLog(@"authorizationCode = %@",authorizationCode);
        
        if (self.completion) {
            NSString *name = nil;
            if (appleIDCredential.fullName.familyName && appleIDCredential.fullName.givenName) {
                name = [NSString stringWithFormat:@"%@%@",appleIDCredential.fullName.familyName,appleIDCredential.fullName.givenName];
            }
            self.completion(nil, appleIDCredential.user, identityToken, name);
        }
    }
    else {
        if (self.completion) {
            self.completion(@"授权失败" ,nil, nil, nil);
        }
    }
}
- (void)authorizationController:(ASAuthorizationController *)controller didCompleteWithError:(NSError *)error  NS_SWIFT_NAME(authorizationController(controller:didCompleteWithError:))  API_AVAILABLE(ios(13.0)) {
    NSLog(@"Handle error：%@", error);
    if (self.completion) {
        self.completion(@"授权失败" ,nil, nil, nil);
    }
}
#pragma mark - ASAuthorizationControllerPresentationContextProviding
- (ASPresentationAnchor)presentationAnchorForAuthorizationController:(ASAuthorizationController *)controller  API_AVAILABLE(ios(13.0)){
    return [UIApplication sharedApplication].windows.lastObject;
}

用户端差不多就是这样来，后续就是api服务器和苹果服务器的验证相关了。

三、服务器验证

推荐大家先看下JWT的教程
然后可以先下苹果授权登陆后端如何验证，我就是看的这篇文章做的验证方案。文章中写了两种方案，我会在后续等下写下我写代码和测试的理解。
有点累，等下再写.........

2020.4.13补充（AppStore已通过审核），刚开始写的上面关于JWT的教程和后端如何验证的链接错了，已修改。
因为在苹果授权登陆后端如何验证已经写的比较完整了，我就补充一细节就好。
1、基于JWT的算法验证
i 先通过Apple的接口（https://appleid.apple.com/auth/keys）获取公钥，转成一个json文件并存到服务器。

公钥接口Postman的截图.jpg

转化成可用公钥.png

identityToken解后的数据.jpg

header.png

payload.png

官方文档.png