ObjectBoxCommand: add new lines to Xcode log output objectbox-swift#300

Also fix typos, highlight target name option.

Author: greenrobot-team

Plugins/GeneratorCommand/ObjectBoxCommand.swift

@@ -131,7 +131,7 @@ struct GeneratorCommand: CommandPlugin {
     if targets.count > 1 {
       let availableTargetNames = targets.map { $0.name }.joined(separator: ", ")
       Diagnostics.error(
-        "Multiple targets found\nPlease select specify one target by using the `--target name` option\nAvailable target names: \(availableTargetNames)"
+        "Multiple targets found\nPlease select specify one target by using the `--target <name>` option\nAvailable target names: \(availableTargetNames)"
       )
       return
     } else if targets.isEmpty {
@@ -170,36 +170,37 @@ struct GeneratorCommand: CommandPlugin {
         Diagnostics.error(
           """
             \(targetNames.count) target names given: \(targetNames)
-            Please select exact 1 target
+            Please select exactly 1 target
           """)
+        return
       }
 
       let targetName = targetNames[0]
 
       var inputFiles: PackagePlugin.FileList?
       for target in context.xcodeProject.targets {
         if target.product?.name == targetName {
-          Diagnostics.remark("Found target \(targetName)")
+          Diagnostics.remark("Found target \(targetName)\n")
           inputFiles = target.inputFiles
         }
       }
 
       if inputFiles == nil {
-        Diagnostics.warning("Target \(targetName) has no files")
+        // File list can be empty, but should never be nil
+        Diagnostics.error("Target \(targetName) has no files\n")
         return
       }
 
-      var sourcesArgs: [String] = []
+      var swiftSourceFiles: [String] = []
       for inputFile in inputFiles! {
         if inputFile.path.string.hasSuffix(".swift") {
-          sourcesArgs.append("--sources")
-          sourcesArgs.append(inputFile.path.string)
+          swiftSourceFiles.append(inputFile.path.string)
         }
       }
 
-      if sourcesArgs.isEmpty {
-        // TODO probably error
-        Diagnostics.warning("No Swift files found in Target \(targetName) ")
+      if swiftSourceFiles.isEmpty {
+        // Only warn in case this is run on a target that has no Swift files
+        Diagnostics.warning("No Swift files found in Target \(targetName)\n")
         return
       }
 
@@ -213,10 +214,10 @@ struct GeneratorCommand: CommandPlugin {
 
       // TODO Add the generated files to the Xcode project
       Diagnostics.remark(
-        "！ Add the generated source file in '\(codeFilePath)' to the project and version control"
+        "！ Add the generated source file in '\(codeFilePath)' to the project and version control\n"
       )
       Diagnostics.remark(
-        "！ Add the generated model file in '\(modelFilePath)' to version control, this is important for ObjectBox model generation"
+        "！ Add the generated model file in '\(modelFilePath)' to version control, this is important for ObjectBox model generation\n"
       )
 
     }