Update Travis config to Xcode 8.3. (#2059)

* Update Travis config to Xcode 8.3.

This also removes the explicit SDK settings, as they should be
controlled through the project instead. It’s also one less setting to
keep up-to-date.

* Limit branch building to master.

.travis.yml

@@ -1,5 +1,8 @@
 language: objective-c
-osx_image: xcode8
+osx_image: xcode8.3
+branches:
+  only:
+    - master
 env:
   global:
   - LC_CTYPE=en_US.UTF-8
@@ -9,23 +12,19 @@ env:
   - MACOS_FRAMEWORK_SCHEME="Alamofire macOS"
   - TVOS_FRAMEWORK_SCHEME="Alamofire tvOS"
   - WATCHOS_FRAMEWORK_SCHEME="Alamofire watchOS"
-  - IOS_SDK=iphonesimulator10.0
-  - MACOS_SDK=macosx10.12
-  - TVOS_SDK=appletvsimulator10.0
-  - WATCHOS_SDK=watchsimulator3.0
   - EXAMPLE_SCHEME="iOS Example"
   matrix:
-    - DESTINATION="OS=3.0,name=Apple Watch - 42mm" SCHEME="$WATCHOS_FRAMEWORK_SCHEME" SDK="$WATCHOS_SDK" RUN_TESTS="NO"  BUILD_EXAMPLE="NO"  POD_LINT="NO"
-    - DESTINATION="OS=2.0,name=Apple Watch - 42mm" SCHEME="$WATCHOS_FRAMEWORK_SCHEME" SDK="$WATCHOS_SDK" RUN_TESTS="NO"  BUILD_EXAMPLE="NO"  POD_LINT="NO"
+    - DESTINATION="OS=3.2,name=Apple Watch - 42mm" SCHEME="$WATCHOS_FRAMEWORK_SCHEME"  RUN_TESTS="NO"  BUILD_EXAMPLE="NO"  POD_LINT="NO"
+    - DESTINATION="OS=2.0,name=Apple Watch - 42mm" SCHEME="$WATCHOS_FRAMEWORK_SCHEME"  RUN_TESTS="NO"  BUILD_EXAMPLE="NO"  POD_LINT="NO"
 
-    - DESTINATION="OS=10.0,name=iPhone 7 Plus"     SCHEME="$IOS_FRAMEWORK_SCHEME"     SDK="$IOS_SDK"     RUN_TESTS="YES" BUILD_EXAMPLE="YES" POD_LINT="YES"
-    - DESTINATION="OS=9.0,name=iPhone 6"           SCHEME="$IOS_FRAMEWORK_SCHEME"     SDK="$IOS_SDK"     RUN_TESTS="YES" BUILD_EXAMPLE="YES" POD_LINT="NO"
-    - DESTINATION="OS=8.1,name=iPhone 4S"          SCHEME="$IOS_FRAMEWORK_SCHEME"     SDK="$IOS_SDK"     RUN_TESTS="YES" BUILD_EXAMPLE="YES" POD_LINT="NO"
+    - DESTINATION="OS=10.3,name=iPhone 7 Plus"     SCHEME="$IOS_FRAMEWORK_SCHEME"      RUN_TESTS="YES" BUILD_EXAMPLE="YES" POD_LINT="YES"
+    - DESTINATION="OS=9.0,name=iPhone 6"           SCHEME="$IOS_FRAMEWORK_SCHEME"      RUN_TESTS="YES" BUILD_EXAMPLE="YES" POD_LINT="NO"
+    - DESTINATION="OS=8.1,name=iPhone 4S"          SCHEME="$IOS_FRAMEWORK_SCHEME"      RUN_TESTS="YES" BUILD_EXAMPLE="YES" POD_LINT="NO"
 
-    - DESTINATION="OS=10.0,name=Apple TV 1080p"    SCHEME="$TVOS_FRAMEWORK_SCHEME"    SDK="$TVOS_SDK"    RUN_TESTS="YES" BUILD_EXAMPLE="NO"  POD_LINT="NO"
-    - DESTINATION="OS=9.0,name=Apple TV 1080p"     SCHEME="$TVOS_FRAMEWORK_SCHEME"    SDK="$TVOS_SDK"    RUN_TESTS="YES" BUILD_EXAMPLE="NO"  POD_LINT="NO"
+    - DESTINATION="OS=10.2,name=Apple TV 1080p"    SCHEME="$TVOS_FRAMEWORK_SCHEME"     RUN_TESTS="YES" BUILD_EXAMPLE="NO"  POD_LINT="NO"
+    - DESTINATION="OS=9.0,name=Apple TV 1080p"     SCHEME="$TVOS_FRAMEWORK_SCHEME"     RUN_TESTS="YES" BUILD_EXAMPLE="NO"  POD_LINT="NO"
 
-    - DESTINATION="arch=x86_64"                    SCHEME="$MACOS_FRAMEWORK_SCHEME"   SDK="$MACOS_SDK"   RUN_TESTS="YES" BUILD_EXAMPLE="NO"  POD_LINT="NO"
+    - DESTINATION="arch=x86_64"                    SCHEME="$MACOS_FRAMEWORK_SCHEME"    RUN_TESTS="YES" BUILD_EXAMPLE="NO"  POD_LINT="NO"
 before_install:
   - gem install cocoapods --pre --no-rdoc --no-ri --no-document --quiet
 script:
@@ -35,21 +34,21 @@ script:
 
   # Build Framework in Debug and Run Tests if specified
   - if [ $RUN_TESTS == "YES" ]; then
-      xcodebuild -workspace "$WORKSPACE" -scheme "$SCHEME" -sdk "$SDK" -destination "$DESTINATION" -configuration Debug ONLY_ACTIVE_ARCH=NO ENABLE_TESTABILITY=YES test | xcpretty;
+      xcodebuild -workspace "$WORKSPACE" -scheme "$SCHEME" -destination "$DESTINATION" -configuration Debug ONLY_ACTIVE_ARCH=NO ENABLE_TESTABILITY=YES test | xcpretty;
     else
-      xcodebuild -workspace "$WORKSPACE" -scheme "$SCHEME" -sdk "$SDK" -destination "$DESTINATION" -configuration Debug ONLY_ACTIVE_ARCH=NO build | xcpretty;
+      xcodebuild -workspace "$WORKSPACE" -scheme "$SCHEME" -destination "$DESTINATION" -configuration Debug ONLY_ACTIVE_ARCH=NO build | xcpretty;
     fi
 
   # Build Framework in Release and Run Tests if specified
   - if [ $RUN_TESTS == "YES" ]; then
-      xcodebuild -workspace "$WORKSPACE" -scheme "$SCHEME" -sdk "$SDK" -destination "$DESTINATION" -configuration Release ONLY_ACTIVE_ARCH=NO ENABLE_TESTABILITY=YES test | xcpretty;
+      xcodebuild -workspace "$WORKSPACE" -scheme "$SCHEME" -destination "$DESTINATION" -configuration Release ONLY_ACTIVE_ARCH=NO ENABLE_TESTABILITY=YES test | xcpretty;
     else
-      xcodebuild -workspace "$WORKSPACE" -scheme "$SCHEME" -sdk "$SDK" -destination "$DESTINATION" -configuration Release ONLY_ACTIVE_ARCH=NO build | xcpretty;
+      xcodebuild -workspace "$WORKSPACE" -scheme "$SCHEME" -destination "$DESTINATION" -configuration Release ONLY_ACTIVE_ARCH=NO build | xcpretty;
     fi
 
   # Build Example in Debug if specified
   - if [ $BUILD_EXAMPLE == "YES" ]; then
-      xcodebuild -workspace "$WORKSPACE" -scheme "$EXAMPLE_SCHEME" -sdk "$SDK" -destination "$DESTINATION" -configuration Debug ONLY_ACTIVE_ARCH=NO build | xcpretty;
+      xcodebuild -workspace "$WORKSPACE" -scheme "$EXAMPLE_SCHEME" -destination "$DESTINATION" -configuration Debug ONLY_ACTIVE_ARCH=NO build | xcpretty;
     fi
 
   # Run `pod lib lint` if specified