Error: Could not resolve SDK path for 'macosx10.8'

这是原因是你当前的系统不是macosx10.8，要在Qt文件中修改。

The problem is that the online installer for Qt currently supports OSX 10.8 (Mountain Lion) by default, and I'm guessing you are on 10.9 (Mavericks) or greater.

There is a workaround:

• Navigate to where you installed Qt (default /Users/your username/Qt) using finder
• Go to the subdirectory 5.3/clang_64/mkspecs directory
• Open the file called qdevice.pri with a text editor
• Change the line !host_build:QMAKE_MAC_SDK = macosx10.8 to:
  • !host_build:QMAKE_MAC_SDK = macosx10.9 if you are on OS X 10.9 (Mavericks), or
  • !host_build:QMAKE_MAC_SDK = macosx if you are on OS X 10.10 (Yosemite)
• Save the file and restart Qt Creator

对于Sierra系统，不要修改成=macosx10.12, 只需要修改成=macosx即可。切记。