That is not an error, Xcode hit a breakpoint that you set.
A breakpoint stops execution of the running program before the highlighted line is executed, allowing you to see the values of variables and step through code to debug. See: https://developer.apple.com/library/ios/recipes/xcode_help-source_editor/Creating,Disabling,andDeletingBreakpoints/Creating,Disabling,andDeletingBreakpoints.html