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Video Tutorial: Swift Scroll View School Part 10: Paging Scroll Views I

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1

In this video tutorial you'll learn about paging scroll views and how to center a page when the user stops scrolling.

This is a companion discussion topic for the original entry at https://www.raywenderlich.com/3911-scroll-view-school/lessons/11
2

For iOS 9, need to change:

tutorialStep.view.setTranslatesAutoresizingMaskIntoConstraints(false)

to

tutorialStep.view.translatesAutoresizingMaskIntoConstraints = false

3

Does anyone know what to put for the verticalConstraints since in iOS 9, the options can not be nil.

4

Does anyone know what to put for the verticalConstraints since in iOS 9, the options can not be nil.

let verticalConstraints = NSLayoutConstraint.constraintsWithVisualFormat("V:|[page1(==view)]|", options: [], metrics: nil, views: views)

5

Hi @jbireton,

You can use : NSLayoutFormatOptions.init(rawValue = 0)

see if that works.

6

Hi, The code doesn’t work for any started kit because xcode is forcing me to use(convert swift2) swift 3.Can you please help?

7

Hi. Here is the code in swift 3:

let verticalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:|[page1(==view)]|", options: .init(rawValue: 0), metrics: nil, views: views)
NSLayoutConstraint.activate(verticalConstraints)

let horizontalConstraints =
    
    NSLayoutConstraint.constraints(withVisualFormat: "H:|[page1(==view)][page2(==view)][page3(==view)][page4(==view)][page5(==view)]|", options: [.alignAllTop, .alignAllBottom], metrics: nil, views: views)

NSLayoutConstraint.activate(horizontalConstraints)
8

The code for keyboard insets works as expected but when i tap on other textfield it keeps on scrolling to the top. I tried using contains method of CGRect but it doesn’t help. How can i control this ?

9

There are a few issues with this example:

First off adding +20 for both hide and show screws up the adjustment value. The -/+ value for the 20 should also be accounted for based on the show value.

let adjustment = ((keyboardFrame.height + 20) * (show ? 1 : -1))

Secondly, keyboardWillShow gets called twice for some reason.

Thirdly, The keyboardFrame height decreases by 45 on the second and subsequent calls.
:expressionless:

10

Can you explain the difference between contentInset and scrollIndcatorInset a bit more? I commented out the scrollIndcatorInset and the results seem to be the same. @bdmoakley

11

@bdmoakley Also, in the challenge when tapping on the other textfields (while the keyboard is still up), the scroll view keeps scrolling up. Is this a bug? It seems that the keyboardWillShow(:) method is called each time you select a different textfield even if the keyboard is already up.