Programming Concepts

MVC

MVC is a the abbreviation for Model view Controller. It is a Object-Oriented Design Pattern

View

Is only in charge for the GUI. It is the slaves of the Controller. It has limited connection to the Controller

action target - It can send an event to the Controller
It can delegate actions, the Controller would be a delegate of the View
It can get data from the controller

Controller

The Controller defines How you Model is presented to the User (UI Logic) Communicates to the View and the Model freely.

Model

The Model is What your application is. It is here were all the algorithms etc. are implemented. It has limited communication to the Controller

Notification & KVO - It can "send out" informations and any body connected can "listen in". KVO = Key-Value Observer

Multiple MVC

For powerful apps multiple MVC's needs to be put together

iOS provides some Controllers whose View is "other MVC's". Examples:
- UITabBarController
- UISplitViewController
- UINavigationController
- UIScrollView

`UITabBarController`

Tab bar can replace top part of the Screen with a different MVC bundle (e.g. Health App)

`UISplitViewController`

Takes two MVC's and puts them side by side (iPad only)

Left MVC = Master
Right MVC = Detail

Landscape mode = Both MVC's side by side Portrait mode = Only Detail view visible, Master view can be siped in from the left

(e.g. Mail)

`NavigationController`

Can push and pop MVC's off of a stack. The Top MVC is shown an with it the Titlebar and left and right button is placed. You can put a MVC into the NavigationController Stack or push them off. The Sub MVC's are created and destroyed at that point.

(e.g. Settings)

`UIScrollView`

Set content size
Add frames to the content area
Reposition the view (the window of the screen inside the screen)
Get area where you're looking at (contentOffset.x & y)

scrollView.contentSize = CGSize(width: 3000, height:2000) // size of the scroll view
// Add logo with 
logo.frame= CGRect(x: 2700, y:50, width: 120, height: 180)
scrollView.addSubview(logo)
// Add another image to the view at a different location
aerial.frame = CGRect(x: 150, y: 200, width: 2500, height:1600)
scrollView.addSubview(aerial)

// Scroll in program
func scrollRectToVisible(CGRect, animated: Bool)

Other things which can be done in scrollView

Enable or disable scrolling
Lock scrolling direction
Style of scrolling indicator (flashScrollIndicator)
Whether your actual content is inset from the content area (contentInset property)

Zooming

All UIView's have a property transform which is an affine transformation (translate, scale, rotate). Zooming is affecting the scroll view contentSize and contentOffset.

// They needed to be set for enabling zoom
scrollView.minimumZoomScale = 0.5 // min half of its normal size
scrollView.maximumZoomScale = 2.0 // max double its normal size

// Will not work without delegate
func viewForZoomingInScrollView(sender: UIScrollView) -> UIView

// Zoom in program
var zoomScale: CGFloat
func setZoomScale(CGFloat, animated: Bool) // Zoom to a different scale (in middle of screen)
func zoomToRect(CGRect, animated: Bool)    // Zoom to a rectangle (fill screen as much as possible)

Accessing Sub MVC's

You can access sub-MVC's via the viewControllers property

var viewControllers: [UIViewController] { get set } // possibly an optional

For a Tabbar they are ordered left to right, in the array.
For a Split View, [0] is the master and [1] is the detail.
For a NavigationController, [0] is the root and the rest are in order on the stack.

Get ahold of the NC, SVC, TBC Every UIViewController knows the SplitView, TabBar or Navigation Controller it is currently in. These are UIViewController properties:

var tabBarController: UITabBarController? { get }
var splitViewController: UISplitViewController? { get }
var navigationController: UINavigationController? { get }
// for example, the get the detail of the split view controller your are in...
if let detailVC: UIViewController = splitViewController?.viewControllers[1] { ... }

Wiring up MVC's

In Story board or Code but Storyboard is more common. For Storyboard

Drag out a SplitViewController
Ctrl drag from SplitViewController to the Master MVC
Ctrl drag from SplitViewController to the Detail MVC
Split View can only work on a Regular size device (iPhone is a compact device). Therefore t can't display Master and Detail on the same screen. The master need to be Embed in a n Navigation Controller
- Select Master
- Editor->Embed In->NavigationController

Segues

Seques are used that one MVC can cause appear another MVC. There are different kind of Segues

Show Segue (will push NavigationCtonroller, else Modal)
Show Detail Segue (will show in Detail of a SplitView or will push in a NavigationController)
Modal Segue ( take over the entire screen while the MVC us up)
Popover Segue () make the MVC appear in a little popover window

Segue always creates new instances of MVC

Creating Segue

Ctrl drag from two View into each other
Click on the Circle in the middle of the segue
Choose an Identifier for the Segue from the Attribute Inspector
Perform Segue in code, with the method from UIViewController. (Not often mosten made in Storyboard)
```
func performSegueWithIdentifier(identifier. String, sender: AnyObject?)
```

Prepare Segue

Identifier are used for preparing for a Segue. A Segue creates a new MVC which is empty, it needs to be prepared with the correct content. A Segue passes two informations:

The Identifier from the Storybaord
The Controller of the MVC you are segueing to (which was just created for you)

sender is the Object from the storyboard (e.g. UIButton) which caused the segue to happen.

func prepareForSegue(segue: UIStoryBoardSegue, sender: AnyObject?) {
  if let identifier = segue.identifier {
      switch identifier {
          case "Show Graph":
              // beause it is anyObject it needs to be turned into the correct class
              if let vc = segue.destinationViewController as? MyController {
                  vc.property1 = ...
                  vc.callMethodToSetUp(...)
              }
          default: break
      }
  }
}

!!! Important. While preparing an MVC its outlet are not set yet.

Prevent Segue

Preventing segue from happening. You need to implement

func shouldPerfromSegueWithIdentifier(identifier: String?, sender: AnyObject?) -> Bool

A popover open en entire MVC. The rest of the screen is grayed out. The Pointer of the Popover points to the button created the Popover.

Popover works with Segue as the other ViewControllers
Preparing for a popover
- All segues are managed via a UIPresentationController

func prepareForSegue(segue: UIStoryBoardSegue, sender: AnyObject) {
    if let identifier = segue.identifier {
        switch identifier {
            case: "Do something in a popover Segue":
                if let vc = segue.destinationViewController as? MyController {
                    // get popover presentation controller
                    if let ppc = vc.popoverPresentationController {
                        ppc.permittedArrowDirections = UIPopoverArrowDirection.Any
                        ppc.delegate = self
                    }
                    // more prepration here
                }
        }
    }
}

The Popover Presentation Delegate (see code above) can manipulate and adapt the popover Adaptation

func adaptivePresentationStyleForPresentationContoller(UIPresentationController) -> UIModelPresentationStyle {
    return UIModalPresentationStyle.None // default .FullScreen
}

FullScreen

func presentationController(UIPresentationController, viewControllerForAdaptivePresentationStyle: UIModalPresentationStyle) -> UIViewController? {
    // return a UIViewController to use (e.g. Wrap Navigation Controller around your MVC)
}

Size Popover should be the needed size of the containing MVC.

var preferredContentSize: CGSize

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