pzheng

https://github.com/leancloud/paas/issues/1008

https://github.com/leancloud/paas/issues/1003

``` { "__type": "Pointer", "className": "Post", "objectId": "55a39634e4b0ed48f0c1845c" } ```

https://forum.leancloud.cn/t/ios/23675

ref: https://docs.swift.org/swift-book/ReferenceManual/Attributes.html

ref: https://developer.apple.com/documentation/cryptokit/insecure

https://github.com/leancloud/swift-sdk/pull/364