Release 2019-04-18 toolchain for macOS.

Author: rxwei

Installation.md

@@ -19,7 +19,7 @@ To install Swift for TensorFlow, download one of the packages below and follow t
 
 | Download | Date | 
 |----------|------|
-| [Xcode 10](https://storage.googleapis.com/swift-tensorflow/mac/swift-tensorflow-DEVELOPMENT-2019-04-16-a-osx.pkg) | April 16, 2019 |
+| [Xcode 10](https://storage.googleapis.com/swift-tensorflow/mac/swift-tensorflow-DEVELOPMENT-2019-04-18-a-osx.pkg) | April 18, 2019 |
 | [Ubuntu 18.04 (CPU Only)](https://storage.googleapis.com/s4tf-kokoro-artifact-testing/latest/swift-tensorflow-DEVELOPMENT-ubuntu18.04.tar.gz) | Nightly | 
 | [Ubuntu 18.04 (CUDA 10.0)](https://storage.googleapis.com/s4tf-kokoro-artifact-testing/latest/swift-tensorflow-DEVELOPMENT-cuda10.0-cudnn7-ubuntu18.04.tar.gz) | Nightly | 
 | [Ubuntu 18.04 (CUDA 9.2)](https://storage.googleapis.com/s4tf-kokoro-artifact-testing/latest/swift-tensorflow-DEVELOPMENT-cuda9.2-cudnn7-ubuntu18.04.tar.gz) | Nightly |
@@ -33,6 +33,7 @@ To install Swift for TensorFlow, download one of the packages below and follow t
 
 | Download |
 |----------|
+| [April 16, 2019](https://storage.googleapis.com/swift-tensorflow/mac/swift-tensorflow-DEVELOPMENT-2019-04-16-a-osx.pkg) |
 | [March 26, 2019](https://storage.googleapis.com/swift-tensorflow/mac/swift-tensorflow-DEVELOPMENT-2019-03-26-a-osx.pkg) |
 | [March 23, 2019](https://storage.googleapis.com/swift-tensorflow/mac/swift-tensorflow-DEVELOPMENT-2019-03-23-a-osx.pkg) |
 | [February 25, 2019](https://storage.googleapis.com/swift-tensorflow/mac/swift-tensorflow-DEVELOPMENT-2019-02-25-a-osx.pkg) |