ios - Xcode7 Core Plot Errors: CPTPlot, NSString -

i'm new both xcode7 , core plot, , i'm trying follow beginner tutorial here: http://www.raywenderlich.com/13269/how-to-draw-graphs-with-core-plot-part-1

everything seems fine until have add code cpdpiechartviewcontroller.m

#pragma mark - cptplotdatasource methods -(nsuinteger)numberofrecordsforplot:(cptplot *)plot {     return 0; }  -(nsnumber *)numberforplot:(cptplot *)plot field:(nsuinteger)fieldenum recordindex:(nsuinteger)index {     return 0; }  -(cptlayer *)datalabelforplot:(cptplot *)plot recordindex:(nsuinteger)index {     return nil; }  -(nsstring *)legendtitleforpiechart:(cptpiechart *)piechart recordindex:(nsuinteger)index {     return @""; }  #pragma mark - uiactionsheetdelegate methods -(void)actionsheet:(uiactionsheet *)actionsheet clickedbuttonatindex:(nsinteger)buttonindex { } 

i number of errors after this: in cpdpiechartviewcontroller.m: (cptplot *) expected type, in cpdconstants.h: unknown type name nsstring (i have ensured there no .c files in xcode project. there other reasons appear?)

i have made screen shot of errors on each file

has dealt before. appreciated!

you're missing import statements in header files. since cpdconstants.h references nsstring, needs foundation @ minimum (#import <foundation/foundation.h>).

cpdpiechartviewcontroller.h , other file references core plot types needs import core plot header. use #import <coreplot/coreplot.h> if included core plot framework or #import "coreplot-cocoatouch.h" if you're using static library.