If your backend uses a secure connection ant you get using NSURLSession
CFNetwork SSLHandshake failed (-9801)
NSURLSession/NSURLConnection HTTP load failed (kCFStreamErrorDomainSSL, -9801)
you need to check your server configuration especially to get ATS version and SSL certificate Info:
Instead of just Allowing Insecure Connection by setting NSExceptionAllowsInsecureHTTPLoads = YES
, instead you need to Allow Lowered Security in case your server do not meet the min requirement (v1.2) for ATS (or better to fix server side).
Allowing Lowered Security to a Single Server
<key>NSExceptionDomains</key>
<dict>
<key>api.yourDomaine.com</key>
<dict>
<key>NSExceptionMinimumTLSVersion</key>
<string>TLSv1.0</string>
<key>NSExceptionRequiresForwardSecrecy</key>
<false/>
</dict>
</dict>
use openssl client to investigate certificate and get your server configuration using openssl client :
openssl s_client -connect api.yourDomaine.com:port //(you may need to specify port or to try with https://... or www.)
..find at the end
SSL-Session:
Protocol : TLSv1
Cipher : AES256-SHA
Session-ID: //
Session-ID-ctx:
Master-Key: //
Key-Arg : None
Start Time: 1449693038
Timeout : 300 (sec)
Verify return code: 0 (ok)
App Transport Security (ATS) require Transport Layer Security (TLS) protocol version 1.2.
Requirements for Connecting Using ATS:
The requirements for a web service connection to use App Transport Security (ATS) involve the server, connection ciphers, and certificates, as follows:
Certificates must be signed with one of the following types of keys:
Secure Hash Algorithm 2 (SHA-2) key with a digest length of at least 256 (that is, SHA-256 or greater)
Elliptic-Curve Cryptography (ECC) key with a size of at least 256 bits
Rivest-Shamir-Adleman (RSA) key with a length of at least 2048 bits An
invalid certificate results in a hard failure and no connection.
The following connection ciphers support forward secrecy (FS) and work
with ATS:
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA
Update: it turns out that openssl only provide the minimal protocol version Protocol : TLSv1 links