Xcode delete subword/word forward/backword eating empty space
If I understand your question correctly given the two lines

abc^
xyz


with the cursor as the ^.
You would like to know how to delete forward to achieve the following with one shortcut

abc^xyz


Again the ^ here symbolizes the text cursor. 

The forward delete in xcode is mapped to both the forward delete key ("del" absent on most mac keyboards) but "fn delete" is a forward delete, "control d" also functions as delete forward. 
This can be changed in the xcode preferences -> keymap 



Now to the aspect of deleting white space and newline... This is harder, it seems like xcodes subword (which selects or deletes to a capitalized section in a word), word, and expression deletes do not include whitespace. 

To select just white space and newline and delete it you can do the following three commands
option shift ->, option shift &lt;-, delete
I have an app called betterTouchTool that allows me to map those three commands to one single one. 
Not my softwware but been using it for years. It's amazing.