I just started to learn Objective C and here are some Xcode 5 shortcuts that I find useful when just getting started with the Editor.

Move cursor back and forth one word.

Shift + Option + Left/Right arrow

Move cursor up and down one line.

Shift + Option + Up/Down arrow

Delete current line where the cursor is located.

Control + k

Open new tab.

Command + T

Close tab.

Command + W

Switch to left or right tab.

Shift + Command + { or }

Open existing file.

Shift + Command + O

Switch between .m and .h file.

Control + Command + Up/Down arrow keys

Run or Build the app

Command + R

Show/Hide Project Navigator

Command + 0