Scroll to the Bottom of a Collection View

private func scrollToBottom() {
    let lastSectionIndex = (collectionView?.numberOfSections())! - 1
    let lastItemIndex = (collectionView?.numberOfItemsInSection(lastSectionIndex))! - 1
    let indexPath = NSIndexPath(forItem: lastItemIndex, inSection: lastSectionIndex)
       
    collectionView!.scrollToItemAtIndexPath(indexPath, atScrollPosition: UICollectionViewScrollPosition.Bottom, animated: false)
}

 

Add a UITableView to an Existing ViewController in Xcode

Quick and dirty checklist for adding a table view to an existing view controller:

  1. Embed existing view controller in a NavigationController
  2. Drag a UITableView object into the view controller in the storyboard
  3. Make the UITableView the same width and height as the view controller and set the constraints to all four sides with no margins
  4. Create an outlet and connection for the tableView in the view controller class
  5. Add UITableViewDataSource and UITableViewDelegate to the class declaration. Your class should look something like this
    import UIKit
     
    class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
     
        @IBOutlet weak var tableView: UITableView!
         
        override func viewDidLoad() {
            super.viewDidLoad()
        }
     
    }
  6. Select the table view, open the connections inspector and connect the table view’s dataSource and delegate methods to the View Controller object.
  7. If you’re not using static cells, open the attributes inspector and set the number of Prototype Cells to 1

Create a Confirmation Alert in iOS with Swift

If you want to present an alert with an option to either take an action or cancel:

@IBAction func clearImage(sender: UIBarButtonItem) {
    let alert = UIAlertController(title: "Clear Canvas", message: "Are you sure you want to clear the canvas?", preferredStyle: .Alert)
    let clearAction = UIAlertAction(title: "Clear", style: .Destructive) { (alert: UIAlertAction!) -> Void in
        self.canvas.image = nil
    }
    let cancelAction = UIAlertAction(title: "Cancel", style: .Default) { (alert: UIAlertAction!) -> Void in
        //print("You pressed Cancel")
    }
        
    alert.addAction(clearAction)
    alert.addAction(cancelAction)
        
    presentViewController(alert, animated: true, completion:nil)
}

 

Create Navigation Bar Programmatically in Swift

In your UIPopoverPresentationControllerDelegate:

func presentationController(controller: UIPresentationController, viewControllerForAdaptivePresentationStyle style: UIModalPresentationStyle) -> UIViewController? {
    let presentedViewController = controller.presentedViewController
    let navigationController = UINavigationController(rootViewController: presentedViewController)
    let dismissButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Done, target: self, action: "dismissPopover:")
        
    presentedViewController.navigationItem.rightBarButtonItem = dismissButton
        
    return navigationController
}
    
func dismissPopover(sender: AnyObject) {
    self.dismissViewControllerAnimated(true, completion: nil)
}

Get user input in Swift

Here is a helper function that handles user input. You can just plop all this in a file called HelperFunctions.swift.

/*

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike
4.0 International License, by Yong Bakos.

*/

import Foundation

// Wait for the user to type something in the console, and return what
// they type as a String with the trailing newline character removed.
func getln() -> String {
    let stdin = NSFileHandle.fileHandleWithStandardInput()
    var input = NSString(data: stdin.availableData, encoding: NSUTF8StringEncoding)
    input = input!.stringByTrimmingCharactersInSet(NSCharacterSet.newlineCharacterSet())
    return input as! String
}