The document discusses iOS view controllers. It explains that a typical iOS app has multiple screens, each implemented with a view controller class. A view controller holds a reference to the UIView that is visible on screen. It describes how to add a button to a view controller's view. It also discusses setting a view controller as the root controller of a window, and implementing the UI in a XIB file. It differentiates between content and container view controllers. It provides an overview of tab bar controllers and navigation controllers, and how they are used to manage multiple screens and hierarchical data in an app.

1. iOS:
View
Controllers
Jussi
Pohjolainen
Tampere
University
of
Applied
Sciences

2. Screen,
Window,
UIView

3. View
Controller

4. 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)

5. UIViewController
#import <UIKit/UIKit.h>
@interface MainScreenViewController :
UIViewController
@end

6. 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];
}

7. 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;
}

8. 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

9. 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!

10. 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!

11. 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

12. Tab
Bar
Controller

13. NavigaMon
Controller

14. Complex
App

15. UITABVIEWCONTROLLER

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

17. UITabController:
Add
Titles
• ViewController
class
has
a
property
tabBarItem!

18. Init
in
more
detail
• The
init
method
here
loads
the
xib-­‐file…
you
pass
the
xib-­‐file
name
to
the
method:

19. 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!

20. UINAVIGATIONCONTROLLER

21. 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

24. 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];

25. Modifying
NavigaMon
Stack
• Add
another
view
to
stack
– [navController
pushViewController:otherViewController
animated:YES];
• To
get
pointer
to
navController
in
ViewController,
use
• [[self
navigationController] pushViewController:otherV
iewController animated:YES];

26. 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];

27. 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]];
}

28. The
Nav
Bar

29. The
Nav
Bar

30. 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

31. Right
BuIon