| targetGuid | The GUID of the target as returned by [[TargetGuidByName()]]. | 
| name | The name of the phase. | 
| dstPath | The destination path. | 
| subfolderSpec | The "subfolder spec". The following usages are known: "13" for embedding app extension content; "16" for embedding watch content. | 
string Returns the GUID of the new phase.
Creates a new copy files build phase for given target.
The new phase is placed at the end of the list of build phases configured for the target.