iOS:  View  Controllers  

Jussi  Pohjolainen  Tampere  University  of  Applied  Sciences  

Screen,  Window,  UIView  

View  Controller  

Several  Screens?  

•  Typical  iOS  app  has  several  screens  •  Usually  this  is  implemented  so  that  you  have  several  View  Controller  classes,  one  for  each  screen  

•  UIViewController  class  holds  a  property  that  points  to  UIView  (which  is  visible  in  the  screen)  

UIViewController  

#import <UIKit/UIKit.h>

@interface MainScreenViewController : UIViewController

@end

Adding  a  BuIon  to  the  View  of  ViewController  

- (void)viewDidLoad

{

[super viewDidLoad];

// Initialize a view, this could be a custom view also..

UIButton* button =

[UIButton buttonWithType:UIButtonTypeRoundedRect];

[button setTitle:@"Main1" forState: UIControlStateNormal];

// Add the view to the controller

[self setView: button];

}

Root  Controller  - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; // Override point for customization after application launch. MainScreenViewController* mainscreen = [[MainScreenViewController alloc] init]; [[self window] setRootViewController:mainscreen]; self.window.backgroundColor = [UIColor whiteColor]; [self.window makeKeyAndVisible]; return YES; }

Root  Controller?  

•  SeKng  a  view  controller  as  root  controller  of  a  window  – Add’s  view  controller’s  view  to  window  – AutomaMcally  resizes  the  view  to  be  the  same  size  than  window  

XIB?  

•  It’s  usually  wise  to  implement  the  UI  in  xib  •  You  can  create  new  empty  xib  file  to  your  project  

•  Set  the  File’s  owner  to  the  view  controller!  

View  Controller  and  View  

•  The  View  Controller  has  a  property  View  •  In  XIB,  you  can  add  to  canvas  a  UIView  and  connect  it  as  outlet  of  the  view  controller’s  view!  

Content  View  Controller  vs  Container  View  Controller  

•  Content  View  Controller  –  Content  on  the  screen  using  Views  – Usually  has  a  .xib  

•  Container  View  Controller  –  Content  owned  by  other  View  Controllers  –  Parent  to  other  controllers  –  Container  manages  a  API  to  manage  children  (change  screens)  

–  For  example:  Tab  Bar  Controller,  Naviga<on  Controller  

Tab  Bar  Controller  

NavigaMon  Controller  

Complex  App  

UITABVIEWCONTROLLER  

UITabController  

•  To  change  a  view  controller  •  Holds  array  of  view  controllers  •  Really  easy  to  implement    

UITabController:  Add  Titles  

•  ViewController  class  has  a  property  tabBarItem!  

Init  in  more  detail  

•  The  init  method  here  loads  the  xib-­‐file…  you  pass  the  xib-­‐file  name  to  the  method:  

Init  in  more  detail  

•  When  iniMalizing  the  controller    –   SettingsViewController* settingsview = [[SettingsViewController alloc] init];

•  This  is  equivalent  to  this!  –  SettingsViewController* settingsview = [[SettingsViewController alloc] initWithNibName:nil bundle:nil];

•  What  happens  if  nibname  is  nil?  –  Search  for  a  xib  file  whose  name  is  the  same  as  your  class  and  search  inside  of  this  app  bundle!

UINAVIGATIONCONTROLLER  

About  Nav  Controller  

•  Presents  data  organized  hierarchically  •  Stack-­‐based  collecMon  of  view  controllers  – Stack:  path  taken  by  the  user  through  the  hierarchical  data  

– BoIom  stack:  starMng  point,  top  stack:  current  posiMon  

•  Holds  – NavigaMon  bar,  a  back  buIon  and  opMonal  custom  views  

CreaMng  a  UINavigaMonController  // Create view controller

SettingsViewController* settingsview = [[SettingsViewController alloc] init];

// Create navigation controller.

// Initialize it with the first screen

UINavigationController* navController =

[[UINavigationController alloc]

initWithRootViewController:settingsview];

// Add navigation controller to window

[[self window] setRootViewController:navController];

Modifying  NavigaMon  Stack  

•  Add  another  view  to  stack  – [navController pushViewController:otherViewController animated:YES];

•  To  get  pointer  to  navController  in  ViewController,  use  •  [[self

navigationController] pushViewController:otherViewController animated:YES];

Passing  informaMon  // Get text from UITextField

NSString* myText = [[self someTextField] text];

// Create the view controller

SettingsView1Controller* sv1 = [[SettingsView1Controller alloc] init];

// Pass the text to the view controller

[sv1 setText: myText];

// Push the view controller to nav controller. viewDidLoad is

// called!

[[self navigationController] pushViewController:sv1 animated:YES];

Receiving  informaMon  @interface SettingsView1Controller : UIViewController { } // Attribute and set+get methods for text @property NSString* text; @property IBOutlet UILabel* label; * * * - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view from its nib.

// Set the given text to label: [[self label] setText: [self text]]; }

The  Nav  Bar  

The  Nav  Bar  

UINavigaMonItem  

•  Set  a  Mtle  –  UINavigationItem *n = [self navigationItem]; –  [n setTitle:@"Settings"];

•  Other  properMes  – MtleView  -­‐>  Can  have  any  view  on  navigaMon  bar  –  rightBarBuIonItem  -­‐>  another  buIon  to  the  right  – See  documentaMon  

Right  BuIon