Xcode full stack trace

Use the bt command in (lldb).

Once paused or after a crash, just type bt into the debug console.
It will print the full stack trace.

In Xcode 5 you can move the slider at the bottom of the pane which shows the stack trace. It controls how much of the struck trace is shown.

In Xcode 6 you can click the button at the bottom left corner of the pane which shows the full stack trace.

You can print the stack trace in the NSLog by

NSLog(@"Stack trace : %@",[NSThread callStackSymbols]);

Upon a crash, next to the word (lldb), you can type:

po [NSThread callStackSymbols]

Edit:

For better output on console on Swift you can use following line instead:

Thread.callStackSymbols.forEach{print($0)}