iOS错误：Undefined symbols for architecture arm64

• Edit your target's Build Settings. Change the value for Architectures by opening the drop down, click on Other... and select it, delete the row with value $(ARCHS_STANDARD) and add two rows with values: armv7 and armv7s (or $(ARCHS_STANDARD_32_BIT) as mentioned by nschum), close the popup.
• Edit the value Valid Architectures and simply remove the arm64 part of it.
• Do it for every nested project you might have inside your workspace or project.

Note: This is not a solution, it's just a few steps to mitigate your current problem, please keep following your dependency projects to find out when they come with arm64 compatibility and revert these settings' change ASAP.

1，编辑的target‘s －》build settings ，改变Architectures选项中的值 ，点击它，选择Other，选中$(ARCHS_STANDARD) 这一行 并删除它，再添加两行，两行的值分别为armv7， armv7s （或者$(ARCHS_STANDARD_32_BIT） 关闭窗口

2， 编辑Valid Architectures 选项的值，删除arm64 这一部分