iphone - confusion with implementing core data -
i beginner , trying move app core data. following big nerd ranch 3rd edition book, in book have store class holds items in item class. app different. have task class , tasks displayed task arrays declared in tableview controller, , if tap on task details come in detail view controller. thing is, book says need create nsmanagedobjectcontext, nsmanagedobjectmodel, , nspersistentstorecoordinator, in store. declare these in app? tableview controller or detail view controller? here code:
tasks.h
#import <foundation/foundation.h> #import <coredata/coredata.h> @interface tasks : nsmanagedobject @property (nonatomic) nsdatecomponents *conversioninfo; @property (nonatomic) nstimeinterval datecreated; @property (nonatomic) double orderingvalue; @property (nonatomic, retain) nsstring * taskname; @property (nonatomic) double timeinterval; @property (nonatomic, retain) nsstring * timeintervalstring; @property (nonatomic, retain) nsmanagedobject *assettype; @end tasks.m
@implementation tasks @dynamic conversioninfo; @dynamic datecreated; @dynamic orderingvalue; @dynamic taskname; @dynamic timeinterval; @dynamic timeintervalstring; @dynamic assettype; -(void)awakefromfetch{ [super awakefromfetch]; } -(void)awakefrominsert{ [super awakefrominsert]; nstimeinterval t = [[nsdate date] timeintervalsincereferencedate]; [self setdatecreated:t]; } -(nsstring *)timeintervalstring{ nscalendar *syscalendar = [nscalendar currentcalendar]; nsdate *date = [nsdate date]; nsdate *date1 = [nsdate datewithtimeinterval:self.timeinterval sincedate:date]; unsigned int unitflags = nshourcalendarunit | nsminutecalendarunit; self.conversioninfo = [syscalendar components:unitflags fromdate:date todate:date1 options:0]; if ([self.conversioninfo hour] == 0){ if ([self.conversioninfo minute] == 1) { self.timeintervalstring = [nsstring stringwithformat:@"%d min", [self.conversioninfo minute]]; } else { self.timeintervalstring = [nsstring stringwithformat:@"%d mins", [self.conversioninfo minute]]; } } else if ([self.conversioninfo hour] == 1) { if ([self.conversioninfo minute] == 0){ self.timeintervalstring = [nsstring stringwithformat:@"%d hr", [self.conversioninfo hour]]; } else if ([self.conversioninfo minute] == 1) { self.timeintervalstring = [nsstring stringwithformat:@"%d hr %d min", [self.conversioninfo hour], [self.conversioninfo minute]]; } else { self.timeintervalstring = [nsstring stringwithformat:@"%d hr %d mins", [self.conversioninfo hour], [self.conversioninfo minute]]; } } else { if ([self.conversioninfo minute] == 0) { self.timeintervalstring = [nsstring stringwithformat:@"%d hrs ", [self.conversioninfo hour]]; } else if ([self.conversioninfo minute] == 1){ self.timeintervalstring = [nsstring stringwithformat:@"%d hrs %d min", [self.conversioninfo hour], [self.conversioninfo minute]]; } else { self.timeintervalstring = [nsstring stringwithformat:@"%d hrs %d mins", [self.conversioninfo hour], [self.conversioninfo minute]]; } } return self.timeintervalstring; } @end tableviewcontroller.m
-(nsmutablearray *)taskarray { if (!taskarray) { taskarray = [nsmutablearray array]; } return taskarray; } -(uitableviewcell *)tableview:(uitableview *)tableview cellforrowatindexpath:(nsindexpath *)indexpath{ cellsubclasscell *cell = [tableview dequeuereusablecellwithidentifier:@"uitableviewcell"]; if (!cell) cell = [[cellsubclasscell alloc]initwithstyle:uitableviewcellstylesubtitle reuseidentifier:@"uitableviewcell"]; if([indexpath section] == 0){ cell.textlabel.text = [[[self.taskarray objectatindex:[indexpath row]] taskname] uppercasestring]; cell.imageview.image = [uiimage imagenamed:@"unchecked.png"]; cell.imageview.highlightedimage = [uiimage imagenamed:@"uncheckedhighlighted.png"]; [cell setaccessorytype:uitableviewcellaccessorydisclosureindicator]; [cell setbackgroundcolor:[uicolor colorwithred:236.0/255 green:240.0/255 blue:241.0/255 alpha:1.0f]]; cell.textlabel.textcolor = basecolor; nsstring *detailtext = [[self.taskarray objectatindex:[indexpath row]] timeintervalstring]; cell.detailtextlabel.text = detailtext; [[cell detailtextlabel] setfont:[uifont fontwithname:@"avenir-black" size:12]]; [[cell textlabel] setfont:[uifont fontwithname:@"avenirnext-demibold" size:16]]; [cell.contentview setalpha:1]; } else if ([indexpath section] == 1) { cell.textlabel.text = [[[self.completedarray objectatindex:[indexpath row]] taskname] uppercasestring]; cell.imageview.image = [uiimage imagenamed:@"checked.png"]; [cell setaccessorytype:uitableviewcellaccessorydisclosureindicator]; [cell setbackgroundcolor:[uicolor colorwithred:236.0/255 green:240.0/255 blue:241.0/255 alpha:1.0f]]; cell.textlabel.textcolor = basecolor; nsstring *detailtext = [[self.completedarray objectatindex:[indexpath row]] timeintervalstring]; cell.detailtextlabel.text = detailtext; [[cell detailtextlabel] setfont:[uifont fontwithname:@"avenir-black" size:12]]; [[cell textlabel] setfont:[uifont fontwithname:@"avenirnext-demibold" size:16]]; [cell.contentview setalpha:0.5]; } uitapgesturerecognizer *tap = [[uitapgesturerecognizer alloc]initwithtarget:self action:@selector(handlechecking:)]; //cell.contentview [cell.imageview addgesturerecognizer:tap]; cell.imageview.userinteractionenabled = yes; return cell; } -(void)tableview:(uitableview *)tableview didselectrowatindexpath:(nsindexpath *)indexpath{ tasks *task = [[tasks alloc]init]; if (indexpath.section == 0){ task.taskname = [[self.taskarray objectatindex:[indexpath row]] taskname]; task.timeinterval = [[self.taskarray objectatindex:[indexpath row]] timeinterval]; task.datecreated = [[self.taskarray objectatindex:[indexpath row]] datecreated]; } else if (indexpath.section == 1){ task.taskname = [[self.completedarray objectatindex:[indexpath row]] taskname]; task.timeinterval = [[self.completedarray objectatindex:[indexpath row]] timeinterval]; task.datecreated = [[self.completedarray objectatindex:[indexpath row]] datecreated]; } detailviewcontroller *dvc = [[detailviewcontroller alloc]init]; [dvc settesttask:task]; [[self navigationcontroller] pushviewcontroller:dvc animated:yes]; } detail view controller.m
@interface detailviewcontroller () @end @implementation detailviewcontroller @synthesize testtask,timer,timerlabel, date1, alertview, components, timeremaining; - (id)initwithnibname:(nsstring *)nibnameornil bundle:(nsbundle *)nibbundleornil { self = [super initwithnibname:nibnameornil bundle:nibbundleornil]; if (self) { } return self; } - (void)viewdidload { [super viewdidload]; [_timeleft setfont:[uifont fontwithname:@"bebasneue" size:25]]; } -(ibaction)starttimer:(id)sender{ [sender sethidden:yes]; [pausebutton sethidden:no]; [continuebutton sethidden:no]; gregoriancalendar = [[nscalendar alloc] initwithcalendaridentifier:nsgregoriancalendar]; self.date1 = [nsdate datewithtimeinterval:[testtask timeinterval] sincedate:[nsdate date]]; timer = [nstimer scheduledtimerwithtimeinterval:1.0 target:self selector:@selector(timeraction:) userinfo:nil repeats:yes]; [timer fire]; } -(void)viewwillappear:(bool)animated{ [super viewwillappear:animated]; [timerlabel setfont:[uifont fontwithname:@"bebasneue" size:60]]; [[self navigationitem] settitle:[testtask taskname]]; if (startbutton.hidden == no){ [pausebutton sethidden:yes]; [continuebutton sethidden:yes]; } else { [pausebutton sethidden:no]; [continuebutton sethidden:no]; } timeremaining = [nsstring stringwithformat:@"%02d:%02d:%02d", [components hour], [components minute], [components second]]; timerlabel.text = timeremaining; [timerlabel setneedsdisplay]; [self.view setneedsdisplay]; } -(void)viewwilldisappear:(bool)animated{ [super viewwilldisappear:animated]; [testtask settaskname:[testtask taskname]]; [testtask settimeinterval:[testtask timeinterval]]; } -(void)timeraction:(nstimer *)t{ nsdate *now = [nsdate date]; components = [gregoriancalendar components:nshourcalendarunit|nsminutecalendarunit|nssecondcalendarunit fromdate:now todate:self.date1 options:0]; timeremaining = nil; if([now compare:self.date1] == nsorderedascending){ timeremaining = [nsstring stringwithformat:@"%02d:%02d:%02d", [components hour], [components minute], [components second]]; nslog(@"works %@", timeremaining); } else { timeremaining = [nsstring stringwithformat:@"00:00:00"]; [self.timer invalidate]; self.timer = nil; if (self.alertview == null){ self.alertview = [[uialertview alloc]initwithtitle:[testtask taskname] message:@"time up!" delegate:self cancelbuttontitle:@"ok" otherbuttontitles:nil, nil]; [alertview performselectoronmainthread:@selector(show) withobject:nil waituntildone:yes]; nslog(@"ended"); } } timerlabel.text = timeremaining; [timerlabel setneedsdisplay]; [self.view setneedsdisplay]; } - (void)alertview:(uialertview *)alertview diddismisswithbuttonindex:(nsinteger)buttonindex{ self.alertview = null; }
you should declare nsmanagedobjectcontext, nsmanagedobjectmodel, , nspersistentstorecoordinator in appdelgate.h file.
all these 3 objects required allocated menory once in application.
need nsmanagedobjectcontext throughout app save/ edit/retrieve managed objects.
my suggestion: create new project, choose master- detail application template. check use core data option.
you template code regarding core data in appdelegate.h , appdelegate.m file of new application can copy/paste in application.
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