Advanced app development for ios. Lab 6 Core Data. Gdańsk 2015 Tomasz Idzi

Transcription

1 Advanced app development for ios Lab 6 Core Data. Gdańsk 2015 Tomasz Idzi

2 Introduction In this lab you will create application which have new control UIPickerView. What s more you'll be familiar with one of the most powerful framework in ios/mac OS X development - Core Data. For this lab, you can get 5 points: 1. Create User Interface 2. Create Data Model 3. Read and Write data 4. Delete data 5. Custom UITableViewCell Create User Interface (1 point) 1. Run Xcode and select Create a new Xcode project 2. From ios section choose Application and Master-Detail Application as a type of template. 3. Choose following options for your project: Product Name: ToDoList. Organization Name: You can leave this blank. Organization Identifier: com.yourname Language: Objective-C Devices: iphone Use Core Data: YES

3 4. Choose place on disk to save a project. 5. From Navigation area which is on the left side of Xcode select file Main.storyboard. 6. In Interface Builder select file View Controller and move to Utilities area, which is on the right side of the Xcode. If you can t see it, probably it s hidden. To open any of hidden part of Xcode window use this buttons: 7. Choose File Inspector section and unselect Use Auto Layout. 8. Choose Attributes Inspector, select iphone-4inch in Size option. 9. Check class AppDelegate, which you can find in project s files on the left side of the Xcode window. There are a few new things, such as properties and methods connected with Core Data. Let's recall what is it: NSManagedObjectContext - The context is a powerful object with a central role in the lifecycle of managed objects, with responsibilities from life-cycle management (including faulting) to validation, inverse relationship handling, and undo/redo. Through a context you can retrieve or fetch objects from a persistent store, make changes to those objects, and then either discard the changes or again through the context commit them back to the persistent store. The context is responsible for watching for changes in its objects and maintains an undo manager so you can have finer-grained control over undo and redo. You can insert new objects and delete ones you have fetched, and commit these modifications to the persistent store. [Apple Inc., (2015) Core Data Framework Reference] NSManagedObjectModel - object describes a schema a collection of entities (data models) that you use in your application. [Apple Inc., (2015) Core Data Framework Reference] NSPersistentStoreCoordinator - associate persistent stores (by type) with a model (or more accurately, a configuration of a model) and serve to mediate between the persistent store or s t o r e s a n d t h e m a n a g e d o b j e c t c o n t e x t o r c o n t e x t s. I n s t a n c e s o f NSManagedObjectContext use a coordinator to save object graphs to persistent storage and to retrieve model information. A context without a coordinator is not fully functional as it cannot access a model except through a coordinator. The coordinator is designed to present a façade to the managed object contexts such that a group of persistent stores appears as an aggregate store. A managed object context can then create an object graph based on the union of all the data stores the coordinator covers. [Apple Inc., (2015) Core Data Framework Reference] 10. Open Main.storyboard and remove all objects. 11. Add NavigationController and new ViewController. Then select NavigationController, open Attribiutes Inspector on the right side of Xcode window and select Is Initial View Controller. Your UI shoudl looks like:

4 12. Select ViewController in Storyboard and set ViewController class 13. To new ViewController add UITableView and to navigation bar add Bar Button Item. Now your ViewController should looks like:

5 14. of UITableView in ViewController. To do it, select TableView in Storyboard and using hold ctrl drag and drop connection in class. 15. as tableview. 16. Add new ViewController to Storyboard. Select Bar Button Item and from this object make a connection to new ViewController and select Push option:

6 16. Run ios Simulator and check if your new ViewController is open after tap on Bar Button Item. 17. Create new class which Inharitance from UIViewController and name it as CreateViewController. 18. Select new ViewController in Storyboard and set CreateViewController as a class of this object. 19. Stay on CreateViewController in Storyboard and add a few objects there - UITextField, UIPickerView and UIButton. Make a connection of those objects. For UIButton create IBAction s method:

7 Create Data Model (1 point) 1. Select ToDoList.xcdatamodeld file which can you find on the left side of Xcode window. 2. Tap Add Entity button. 3. Double-click on new Entity and rename it to Task.

8 4. Select Task entity and add two attributes: name - String type priority - Integer Generating class files of Core Data s entity: Change Editor Style to Table, Graph (you can find it on the right-bottom of xcdatamodeld file): Select Task entity: Select File>New>File Select Core Data in ios section and NSManagedObject subclass

9 Select ToDoList as model data and Task as entity. After tap on create button you should see Task.h and Task.m files. Read and write data (1 point) 1. Open CreateViewController and add UIPicerViewDelegate, UIPickerViewDataSource nad CreateViewController () <UIPickerViewDelegate, UIPickerViewDataSource> NSArray 2. In viewdidload method set delegates and create NSSArray of picker s objects. - (void)viewdidload [super viewdidload]; self.pickerview.delegate = self; self.pickerview.datasource = self; _pickerdata 3. Implement UIPickerViewDelegate and UIPickerViewDataSource methods: - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerview return 1; - (NSInteger)pickerView:(UIPickerView *)pickerview numberofrowsincomponent:(nsinteger)component return _pickerdata.count; - (NSString*)pickerView:(UIPickerView *)pickerview titleforrow: (NSInteger)row forcomponent:(nsinteger)component return [NSString stringwithformat:@"%ld",(long) [_pickerdata[row]integervalue]];

10 4. Create private method in CreateViewController.m to implement save data to Core Data (don t forget to import AppDelegate and Task class). - (BOOL)createNewTaskWithName:(NSString*)name andpriority: (NSNumber*)priority AppDelegate *appdelegate = (AppDelegate*)[[UIApplication sharedapplication] delegate]; NSManagedObjectContext *managedobjectcontext = appdelegate.managedobjectcontext; BOOL result = NO; Task *newtask = [NSEntityDescription insertnewobjectforentityforname:@"task" inmanagedobjectcontext:managedobjectcontext]; if (!newtask) return NO; newtask.name = name; newtask.priority = priority; NSError *error; if ([managedobjectcontext save:&error]) result = YES; return result; 5. Implement IBAction method - (IBAction)create:(id)sender NSNumber *priority = [_pickerdata objectatindex:[self.pickerview selectedrowincomponent:0]]; if ([self createnewtaskwithname:self.textfield.text andpriority:priority]) [self.navigationcontroller popviewcontrolleranimated:yes]; 6. Open ViewController.m class and add delegates and to private interface.

11 @interface ViewController () <UITableViewDelegate, UITableViewDataSource, (strong, nonatomic) NSFetchedResultsController 7. Add methods to get data from Core Data - (NSManagedObjectContext *)managedobjectcontext AppDelegate *appdelegate = (AppDelegate *)[[UIApplication sharedapplication]delegate]; NSManagedObjectContext *managedobjectcontext = appdelegate.managedobjectcontext; return managedobjectcontext; - (void)getfetchresultcontroller NSFetchRequest *fetchrequest = [NSFetchRequest new]; NSEntityDescription *entity = [NSEntityDescription entityforname:@"task" inmanagedobjectcontext:[self managedobjectcontext]]; NSSortDescriptor *prioritysort = [[NSSortDescriptor alloc] initwithkey:@"priority" ascending:yes]; NSArray *sortdescription fetchrequest.sortdescriptors = sortdescription; [fetchrequest setentity:entity]; if (!self.taskfetchresultcontroller) self.taskfetchresultcontroller = [[NSFetchedResultsController alloc] initwithfetchrequest:fetchrequest managedobjectcontext:[self managedobjectcontext] sectionnamekeypath:nil cachename:nil]; self.taskfetchresultcontroller.delegate = self; NSError *error; if ([self.taskfetchresultcontroller performfetch:&error]) NSLog(@"Data fatched"); else NSLog(@"Can't fatched data");

12 7. Override viewdidload methods where you set UITableView s delegates and method to reload UITableView when some changes in Core Dara are made: - (void)viewdidload [super viewdidload]; self.tableview.delegate = self; self.tableview.datasource = self; [self getfetchresultcontroller]; - (void)controllerdidchangecontent:(nsfetchedresultscontroller *)controller [self.tableview reloaddata]; 8. Implement UITableView delegate s methods - (NSInteger)tableView:(UITableView *)tableview numberofrowsinsection: (NSInteger)section id <NSFetchedResultsSectionInfo> sectioninfo = [self.taskfetchresultcontroller.sections objectatindexedsubscript:section]; return [sectioninfo numberofobjects]; - (UITableViewCell *)tableview:(uitableview *)tableview cellforrowatindexpath:(nsindexpath *)indexpath static NSString *CellIdentifier UITableViewCell *cell = [tableview dequeuereusablecellwithidentifier:cellidentifier]; if (cell == nil) cell = [[UITableViewCell alloc] initwithstyle:uitableviewcellstyledefault reuseidentifier:cellidentifier]; // Set the data for this cell: Task *task = [self.taskfetchresultcontroller objectatindexpath:indexpath]; cell.textlabel.text = task.name; return cell; 9. Run ios Simulator and add some values to Core Data.

13 Delete data (1 point) 1. Select ViewController and add methods to delete objets in Core Data. - (void)tableview:(uitableview *)tableview commiteditingstyle: (UITableViewCellEditingStyle)editingStyle forrowatindexpath: (NSIndexPath *)indexpath Task *tasktodelete = [self.taskfetchresultcontroller objectatindexpath:indexpath]; self.taskfetchresultcontroller.delegate = nil; [[self managedobjectcontext] deleteobject:tasktodelete]; if ([tasktodelete isdeleted]) NSError *error; if ([[self managedobjectcontext] save:&error]) NSError *fetchingerror; if ([self.taskfetchresultcontroller performfetch:&fetchingerror]) NSArray *rowstodelete [self.tableview deleterowsatindexpaths:rowstodelete withrowanimation:uitableviewrowanimationautomatic]; self.taskfetchresultcontroller.delegate = self; - (UITableViewCellEditingStyle)tableView:(UITableView *)tableview editingstyleforrowatindexpath:(nsindexpath *)indexpath return UITableViewCellEditingStyleDelete; 2. Now when you swipe to left on UITableViewCell you will see delete button and when you tap on it object from Core Data will be delete.

14 Custom UITableViewCell (1 point) 1. Change color of teh UITableViewCell depent on priority of the task.