Use relative paths for pbxFiles

Author: tdermendjiev

lib/pbxProject.js

@@ -318,9 +318,8 @@ pbxProject.prototype.addPbxGroup = function (filePathsArray, name, path, sourceT
             isa: 'PBXGroup',
             children: [],
             name: name,
-            path: path,
             sourceTree: sourceTree ? sourceTree : '"<group>"'
-        },
+        },//path is mandatory only for the main group
         fileReferenceSection = this.pbxFileReferenceSection(),
         filePathToReference = {};
 
@@ -335,6 +334,7 @@ pbxProject.prototype.addPbxGroup = function (filePathsArray, name, path, sourceT
     }
 
     for (var index = 0; index < filePathsArray.length; index++) {
+        
         var filePath = filePathsArray[index],
             filePathQuoted = "\"" + filePath + "\"";
         if (filePathToReference[filePath]) {
@@ -345,7 +345,8 @@ pbxProject.prototype.addPbxGroup = function (filePathsArray, name, path, sourceT
             continue;
         }
 
-        var file = new pbxFile(filePath);
+        var srcRootPath = $path.join(this.filepath, "../..");
+        var file = new pbxFile($path.relative(srcRootPath, filePath));
         if (fs.lstatSync(filePath).isDirectory()) {
             file.uuid = this.generateUuid();
             file.fileRef = file.uuid;
@@ -375,7 +376,7 @@ pbxProject.prototype.addPbxGroup = function (filePathsArray, name, path, sourceT
     if (opt.isMain) {
         let mainGroup = this.findMainPbxGroup();
         if (mainGroup) {
-            var file = new pbxFile(pbxGroup.path);
+            var file = new pbxFile($path.relative(this.filepath, path));
             file.fileRef = pbxGroupUuid;
             mainGroup.children.push(pbxGroupChild(file));
         }