Make multi platform targets parse deployment target per platform.

CHANGELOG.md

@@ -5,6 +5,7 @@
 #### Added
 - Added `missingConfigFiles` to `options.disabledValidations` to optionally skip checking for the existence of config files.
 - Added ability to automatically include Carthage related dependencies via `includeRelated: true` [#506](https://github.com/yonaskolb/XcodeGen/pull/506) @rpassis
+- Added ability to customize deployment target for Multi Platform targets. [#510](https://github.com/yonaskolb/XcodeGen/pull/510) @ainopara
 
 #### Fixed
 - Sources outside a project spec's directory will be correctly referenced as relative paths in the project file. [#524](https://github.com/yonaskolb/XcodeGen/pull/524)

Docs/ProjectSpec.md

@@ -256,6 +256,7 @@ This will provide default build settings for a certain platform. It can be any o
 **Multi Platform targets**
 
 You can also specify an array of platforms. This will generate a target for each platform.
+If deployment target is specified, it will be used for these targets. Or else deplyment target specified in [Options](#options) will be used.
 If you reference the string `$platform` anywhere within the target spec, that will be replaced with the platform.
 
 The generated targets by default will have a suffix of `_$platform` applied, you can change this by specifying a `platformSuffix` or `platformPrefix`.
@@ -267,6 +268,9 @@ targets:
   MyFramework:
     sources: MyFramework
     platform: [iOS, tvOS]
+    deploymentTarget:
+      iOS: 9.0
+      tvOS: 10.0
     type: framework
     settings:
       base:

Sources/ProjectSpec/Target.swift

@@ -194,6 +194,9 @@ extension Target {
                     }
                     platformTarget["productName"] = targetName
                     platformTarget["settings"] = settings
+                    if let deploymentTargets = target["deploymentTarget"] as? [String: Any] {
+                        platformTarget["deploymentTarget"] = deploymentTargets[platform]
+                    }
                     crossPlatformTargets[newTargetName] = platformTarget
                 }
             } else {

Tests/XcodeGenKitTests/SpecLoadingTests.swift

@@ -310,6 +310,7 @@ class SpecLoadingTests: XCTestCase {
             $0.it("parses cross platform targets") {
                 let targetDictionary: [String: Any] = [
                     "platform": ["iOS", "tvOS"],
+                    "deploymentTarget": ["iOS": 9.0, "tvOS": "10.0"],
                     "type": "framework",
                     "sources": ["Framework", "Framework $platform"],
                     "settings": ["SETTING": "value_$platform"],
@@ -323,6 +324,8 @@ class SpecLoadingTests: XCTestCase {
                 target_tvOS.sources = ["Framework", "Framework tvOS"]
                 target_iOS.settings = ["PRODUCT_NAME": "Framework", "SETTING": "value_iOS"]
                 target_tvOS.settings = ["PRODUCT_NAME": "Framework", "SETTING": "value_tvOS"]
+                target_iOS.deploymentTarget = Version(major: 9, minor: 0, patch: 0)
+                target_tvOS.deploymentTarget = Version(major: 10, minor: 0, patch: 0)
 
                 try expect(project.targets.count) == 2
                 try expect(project.targets) == [target_iOS, target_tvOS]