algal

// known confusing on Swift 2.1, Xcode 7.1 

import Foundation

public class InnerMutator {
  var f:(() -> Void)?
}

public struct MutableValue
{

algal

/// Exposes all colors in a gradient, which is defined as usual by a finite number of color stops
/// - version: known good on Xcode 7.1 playgrounds and iOS 9.1
class ColorGradient
{
  // array of specified colors for specified locations along the gradient
  let colors:[UIColor]
  // array of specified locations (in 0...1) for the specified colors in the gradient
  let locations:[CGFloat]
  
  let gradientImage:UIImage

algal

/// Given `path`, drawn with `width`, returns a new path outlining its edges
func pathOutliningPath(path:UIBezierPath, withWidth width:CGFloat, inSize size:CGSize) -> UIBezierPath
{
  UIGraphicsBeginImageContextWithOptions(size, false, 0)
  let ctx = UIGraphicsGetCurrentContext()
  CGContextSetLineWidth(ctx, width)
  CGContextAddPath(ctx, path.CGPath)
  CGContextReplacePathWithStrokedPath(ctx)
  let extractedCGPath = CGContextCopyPath(ctx)
  UIGraphicsEndImageContext()

algal

let v = UIView()
// use `performSelector` to workaround that the method is private
// use `takeRetainedValue` to get an AnyObject
// use the forced cast because we know it's a string
let s = v.performSelector("recursiveDescription").takeRetainedValue() as! String
// convert the string to a fixed width font, so the quicklook is useful
NSAttributedString(string: s, attributes: [UIFontDescriptorFeatureSettingsAttribute:[UIFontFeatureTypeIdentifierKey:kMonospacedTextSelector]])

algal

//: Playground - noun: a place where people can play

import UIKit

/*:

This playground shows a bug in how `NSAttributedString.boundingRectWithSize(_:options:context:)` handles attributed strings containing the LINE SEPARATOR character when the .UsesDeviceMetrics option is not included.

When the `.UsesDeviceMetrics` option is set, the function is supposed to return the bounding rect where the height is what is required to bound the particular glyphs in the string.

algal

import UIKit

//: # Paragraphs, lines, breaks, and spacing in attributed strings

/*:
The cocoa text system lets you separately adjust line spacing and paragraph spacing.

This playground investigates a few questions concerning these spacing configurations and text layout:

1. Do empty UILabels collapse to zero height?

algal

// Swift 1.2
// synchronous JSON download

import XCPlayground

// my goodness all this complexity is just for an unconditional synchronous
// get in a playground on HTTP or HTTPS and decoding to JSON. sad.

public func waitUntilTrue(@autoclosure pred:()->Bool, secondsUntilTimeout duration:NSTimeInterval = 25)
{

algal

// works as of Swift 1.2, 2015-08-29

// https://developer.apple.com/library/ios/technotes/tn2232/_index.html#//apple_ref/doc/uid/DTS40012884-CH1-SECNSURLSESSION

class NSURLSessionAllowBadCertificateDelegate : NSObject, NSURLSessionDelegate
{
  func URLSession(session: NSURLSession, didReceiveChallenge challenge: NSURLAuthenticationChallenge, completionHandler: (NSURLSessionAuthChallengeDisposition, NSURLCredential!) -> Void)
  {
    if challenge.protectionSpace.authenticationMethod == NSURLAuthenticationMethodServerTrust
    {

algal

// in a playground, pause execution wait until the condition pred is true
func waitUntilTrue(@autoclosure pred:()->Bool, secondsUntilTimeout duration:NSTimeInterval = 25)
{
  let previousPlayGroundRunStatus = XCPExecutionShouldContinueIndefinitely()
  XCPSetExecutionShouldContinueIndefinitely(continueIndefinitely: true)
  
  let start = NSDate()
  while true {
    if pred() {
      NSLog("condition met.")

algal

// code from: http://stackoverflow.com/questions/2451223/uibutton-how-to-center-an-image-and-a-text-using-imageedgeinsets-and-titleedgei/24294816#24294816

extension UIButton {
  func centerLabelVerticallyWithPadding(spacing:CGFloat) {
    // update positioning of image and title
    let imageSize = self.imageView.frame.size
    self.titleEdgeInsets = UIEdgeInsets(top:0,
                                        left:-imageSize.width,
                                        bottom:-(imageSize.height + spacing),
                                        right:0)