最近调试SDWebImage加载自签的https图片时怎么也无法绕过验证。

换个思路，将自签证书导入到SDWebimage使用的URLSession中。

具体方法如下：

在SDWebimageDownloader.m中添加URLSession代理方法

- (void)URLSession:(NSURLSession *)session didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition, NSURLCredential * _Nullable credential))completionHandler{
NSLog(@"证书认证");
if ([[[challenge protectionSpace] authenticationMethod] isEqualToString: NSURLAuthenticationMethodServerTrust]) {
do{
    SecTrustRef serverTrust = [[challenge protectionSpace] serverTrust];
    NSCAssert(serverTrust != nil, @"serverTrust is nil");
    if(nil == serverTrust)                break;
    /* failed */
    /**
     *  导入多张CA证书（Certification Authority，支持SSL证书以及自签名的CA），请替换掉你的证书名称
     */
    NSString *cerPath = [[NSBundle mainBundle] pathForResource:@"证书名字_cerName" ofType:@"cer"];
    //自签名证书
    NSData* caCert = [NSData dataWithContentsOfFile:cerPath];

    NSCAssert(caCert != nil, @"caCert is nil");
    if(nil == caCert)                break;
    /* failed */
    SecCertificateRef caRef = SecCertificateCreateWithData(NULL, (__bridge CFDataRef)caCert);
    NSCAssert(caRef != nil, @"caRef is nil");
    if(nil == caRef)                break;
    /* failed */
    //可以添加多张证书
    NSArray *caArray = @[(__bridge id)(caRef)];
    NSCAssert(caArray != nil, @"caArray is nil");
    if(nil == caArray)                break;
    /* failed */
    //将读取的证书设置为服务端帧数的根证书
    OSStatus status = SecTrustSetAnchorCertificates(serverTrust, (__bridge CFArrayRef)caArray);
    NSCAssert(errSecSuccess == status, @"SecTrustSetAnchorCertificates failed");
    if(!(errSecSuccess == status))                break;
    /* failed */
    SecTrustResultType result = -1;
    //通过本地导入的证书来验证服务器的证书是否可信
    status = SecTrustEvaluate(serverTrust, &result);
    if(!(errSecSuccess == status))                break;
    /* failed */
    NSLog(@"stutas:%d",(int)status);
    NSLog(@"Result: %d", result);
    BOOL allowConnect = (result == kSecTrustResultUnspecified) || (result == kSecTrustResultProceed);
    if (allowConnect) {
        NSLog(@"success");
    }else {
        NSLog(@"error");
    }

    /* kSecTrustResultUnspecified and kSecTrustResultProceed are success */
    if(! allowConnect)            {
        break;
        /* failed */
    }
    #if 0
    /*
     Treat kSecTrustResultConfirm and kSecTrustResultRecoverableTrustFailure as success 
     */

    /*   since the user will likely tap-through to see the dancing bunnies */
    if(result == kSecTrustResultDeny || result == kSecTrustResultFatalTrustFailure || result == kSecTrustResultOtherError)                break;
    /* failed to trust cert (good in this case) */
    #endif
    // The only good exit point
    NSLog(@"信任该证书");
    NSURLCredential *credential = [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust];
    completionHandler(NSURLSessionAuthChallengeUseCredential,credential);

    return [[challenge sender] useCredential: credential forAuthenticationChallenge: challenge
];
}while(0);
}
// Bad dog
NSURLCredential *credential = [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust];
completionHandler(NSURLSessionAuthChallengeCancelAuthenticationChallenge,credential);

return [[challenge sender] cancelAuthenticationChallenge: challenge];
}

在 证书名字_cerName 的位置填上自签证书的名字，即可将证书导入到SDWebimage的请求中，也可以添加多张证书。