To make it light, put this inside the View Controller class:

override func preferredStatusBarStyle() -> UIStatusBarStyle {
    return .LightContent
}

Or to hide it completely:

override func prefersStatusBarHidden() -> Bool {
  return true
}

Tell the scrollView to be the same size as the imageView:

scrollView.contentSize = imageView.frame.size

Or, set it to a pixel size:

scrollView.contentSize = CGSize(width:375, height:1857)

Define the first [0] of the child view controllers with the class name ChildViewControllerClassName as a variable childVC:

let childVC = self.childViewControllers[0] as! ChildViewControllerClassName

Put childVC. before the var you want to control from the child VC:

childVC.thingToControl.alpha = 1

Dismiss a modal:

dismissViewControllerAnimated(true, completion: nil)

Go back in the history stack:

navigationController!.popViewControllerAnimated(true)

viewDidLoad() only runs the first time a view loads. If you want to do something when you pop a view try viewDidAppear() or viewWillAppear().

override func viewDidAppear(animated: Bool) {
}

let scrollTo = CGPointMake(0.0, 57.0)
scrollView.setContentOffset(scrollTo, animated: true)

In the view controller that you want to receive the variable, set an empty variable and give it a type.

var emptyVariableInDestinationViewController: Bool!

In Source View Controller:

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject!) {
  // Set the destination view controller name at the end of this line.
  let destinationVC = segue.destinationViewController as! DestinationViewControllerClassName
  // Give it a value at the end of this line.
  destinationVC.emptyVariableInDestinationViewController = thingIWantToSetItTo
}

In viewDidLoad():

self.automaticallyAdjustsScrollViewInsets = false

See this commit.

Most common properties in a gesture. These are CGPoints, add .x or .y for axis:

let location = sender.locationInView(view)
let translation = sender.translationInView(view)
let velocity = sender.velocityInView(view)

These states go inside the gesture recognizer method:

if sender.state == .Began {
  // Runs once on start of gesture
}
if sender.state == .Changed {
  // Runs constantly as the gesture changes
}
if sender.state == .Ended {
  // Runs once when the gesture ends
}

Go to Settings > Keybindings to remap or add keyboard shortcuts. When removing existing keybindings, don't press the keyboard Delete key, click the – icon. Some keybindings can't be deleted ¯\_(ツ)_/¯; remap these to keybindings that are available.

Xcode has something called "Edit All in Scope" (ctrl + cmd + e). It's similar but just selects all instances of the selected text.

command + shift + o

There aren't actually commands for Delete Line and Duplicate Line, but you can edit a plist file to chain multiple actions together into one command. After editing the .plist you can add a shortcuts in Settings > Keybindings.

Open /Applications/Xcode.app/Contents/Frameworks/IDEKit.framework/Resources/IDETextKeyBindingSet.plist and put this before the closing </dict> and </plist> tags:

<key>Custom</key>
<dict>
  <key>Delete Line</key>
  <string>moveToEndOfLine:, deleteToBeginningOfLine:, deleteToEndOfParagraph:</string>
  <key>Duplicate Line</key>
  <string>moveToBeginningOfLine:, deleteToEndOfLine:, yank:, insertNewline:, moveToBeginningOfLine:, yank:</string>
</dict>

There are commands for Move Line Up and Move Line Down (cmd + option + [/]).

This NSHipster Article covers a lot of other shortcuts.