HanXu questions

• Sound is not played in push notifications
• Spark saving RDD[(Int, Array[Double])] to text file got strange result
• Neo4j create if not exist otherwise update
• Select some from many binary sequences so that the result of "or" them together is 1111111111....111
• pg_trgm behaves differently on Ubuntu and Mac OS X
• Why can Apple declare optional protocol funcs without @objc, and unowned optional variables, but I can't?
• How to do GPU programming on Macbook Air?
• layoutSubviews in UIViewTableCell does not work
• Deduction guide for variadic template constructor fails
• NSAttributedString changed font unexpectedly after inserting Image

HanXu answers