I copied a file from projectA to projectB but forgot to tick Copy items if needed. Unbeknownst to me a couple of weeks later when I deleted projectA the SettingsController file in projectB got deleted along with it. Afterwards in projectB the error Build input file cannot be found ... path/Folder/toSomeFile was shown.
为了解决这个问题,我关闭了 Xcode,进入它所在的主文件夹,打开文件夹,右键点击扩展名为 .xcodeproj的 蓝色 Xcode 图标,然后选择 Show Package Contents