objective c - ios error terminating -[__NSArrayM setRoleHistorys:]: -

im trying make user role page data login. created own delegate function call webservice app getting crash due to-[__nsarraym setrolehistorys:]: unrecognized selector sent instance. here code: in .m file :

- (void)parserdidstartdocument:(nsxmlparser *)parser {   nodecontent = [[nsmutablestring alloc]init]; }  - (void)parserdidenddocument:(nsxmlparser *)parser {   arrayitems = [[nsmutablearray alloc] init]; u serroledataparser *userroleparser = [[userroledataparser alloc] init];   // userrole *currentstudent = (userrole *) arrayitems; nsstring *username = username.text; nslog(@"the string value%@",username); [userroleparser getuserhistoryforindex:0 loginid:username.text];  nslog(@"the string user value %@",username.text); userroleparser.delegate = self;  } - (void) didrecievedata : (nsarray *) userhistories forindex :(int) index  { arrayitems = [[nsmutablearray alloc] init]; userrole *roles = (userrole *) arrayitems; roles.rolehistorys = userhistories; datadisplay.text = roles.role; nslog(@"the success data%@", datadisplay.text);  } 

in delegate file .h

 @interface userrole : nsobject  @property (nonatomic,copy)  nsstring *username;  @property (nonatomic,copy)  nsstring *role; @property (nonatomic,copy)  nsstring *empcode;  @property (nonatomic,copy)nsmutablearray * rolehistorys; @end 

dataparser.h file (delegate)

#import <foundation/foundation.h>  #import "userrole.h"   @protocol userroledataparserdelegate <nsobject>   - (void) didrecievedata : (nsarray *) userhistories forindex :(int) index ;   @end   @interface userroledataparser : nsobject<nsxmlparserdelegate> {  nsmutabledata *xmldata; nsxmlparser *userroleparser; nsmutablestring *capturedstring; bool capturecharacters; nsmutablearray *userhistories; }  - (void) getuserhistoryforindex : (int) index loginid :(nsstring*) loginid;   @property (weak,nonatomic) id <userroledataparserdelegate> delegate;  @property (nonatomic) int index;  @end 

am getting output in nslog app getting crash.

this code isn't correct:

arrayitems = [[nsmutablearray alloc] init]; userrole *roles = (userrole *) arrayitems; 

you can't cast array custom class type (unless have subclassed nsmutablearray , instance of subclass type). need create instance of or find correct instance want before try use it.