xcode The document “...“ could not be saved

Today when I tried to save a file on my project I get an error message saying: The document “nameOfFile.m” could not be saved. I tried reinstalling xcode but no luck. The file can be edited with other editors and I see the same behavior on all my projects as well as newly created projects. Any ideas?

解决：重新启动了 XCode（通过强制退出，而不仅仅是关闭它），这为我修复了它