Method1(親測有效):
target -> Build Settings -> 搜索weak -> 切換WeakReferences in Manual Retain Release的值為No (No->Yes->No)
Method2:
進入Preferences…-> Text Editing

Method3:
退出Xcode,重啟電腦,前往文件夾~/Library/Caches/com.apple.dt.Xcode并刪除,并刪除DerivedData,重新運行Xcode