iOS Run Loop, What Why When
https://prafullkumar77.medium.com/ios-run-loop-what-why-when-7febead400b7
Official documentation:
簡單聊聊 iOS Run Loop
https://medium.com/@chengyang1380/%E7%B0%A1%E5%96%AE%E8%81%8A%E8%81%8A-ios-run-loop-a9204314b773
What is a RunLoop Anyway? Swift and iOS Guide
比較RunLoop default mode & common mode:
https://stackoverflow.com/questions/7222449/nsdefaultrunloopmode-vs-nsrunloopcommonmodes