Difference between revisions of "Swift code snippets"

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=Swift Code snippts=
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=Swift Code Snippts=
 
Back To [[IOS_Swift]]
 
Back To [[IOS_Swift]]
==Making Network Request==
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==[[Swift: Use NSUserDefaults to Store Persistence Data]]==
<pre class="brush:swift">
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var clientId = "Put your client id here"
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var url = NSURL(string: "https://api.instagram.com/v1/media/popular?client_id=\(clientId)")!
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var request = NSURLRequest(URL: url)
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NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue()) { (response: NSURLResponse!, data: NSData!, error: NSError!) -> Void in
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    var responseDictionary = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: nil) as NSDictionary
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    self.photos = responseDictionary["data"] as NSArray
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    self.tableView.reloadData()
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    println("response: \(self.photos)")
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}
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</pre>
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==Use AFNetworking setImageWithURL==
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==[[Swift: Making Network Request Using NSURLConnection]]==
Create the bridging file: create a new Objective-C file, name it anything, and when you save it, Xcode will prompt you generate a bridging file. <br>
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In an Objective-C bridging file:
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<pre class="brush:swift">
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#import <AFNetworking/UIImageView+AFNetworking.h>
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</pre>
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In the swift view file, to set a imageView using URL:
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<pre class="brush:swift">
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setImageWithURL(NSURL(string: thumbnailURL))
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</pre>
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==Adding UIRefreshControl==
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==[[Swift:Use AFNetworking setImageWithURL]]==
<pre class="brush:swift">
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//refreshControl is automatically defined in UITableViewController
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var refreshControl: UIRefreshControl?
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override func viewDidLoad() {
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    super.viewDidLoad()
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    refreshControl = UIRefreshControl()
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    refreshControl?.addTarget(self, action: "fetch", forControlEvents: UIControlEvents.ValueChanged)
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    tableView.insertSubview(refreshControl!, atIndex: 0)
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}
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//to stop refresh, call
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==[[Swift:Using UIRefreshControl]]==
if let rc = self.refreshControl {
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    self.refreshControl!.endRefreshing()
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}
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</pre>
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==Example of fetching messages from Parse==
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==[[Swift:Using UIGestureRecognizer]]==
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==Swift:Example of fetching messages from Parse==
 
https://gist.github.com/sandofsky/7134b1ff90d235901254
 
https://gist.github.com/sandofsky/7134b1ff90d235901254
==Auto Table Row Height==
 
<pre class="brush:swift">
 
//Auto table row height
 
tableView.estimatedRowHeight = 92.0
 
tableView.rowHeight = UITableViewAutomaticDimension
 
</pre>
 
==Navigation between storyboards==
 
===Navigate to Storyboard ID===
 
<pre class="brush:swift">
 
var vc = storyboard.instantiateViewControllerWithIdentifier("loginViewController") as UIViewController
 
window?.rootViewController = vc
 
</pre>
 
===Navigate Segue by Identifier===
 
First, drag a segue in storyboard and give it an identifier, then in the button action (or any action you like), do:
 
<pre class="brush:swift">
 
self.performSegueWithIdentifier("loginSegue", sender: self)
 
</pre>
 
===Get UIVewController from Navigation Controller===
 
Sometimes, you want to access the UIViewController from a navigation controller
 
<pre class="brush:swift">
 
var vc = storyboard?.instantiateViewControllerWithIdentifier("navigationID") as UINavigationController
 
var v = vc.viewControllers[0] as ViewController // [0] represents the first level UIViewController under NavigationController
 
</pre>
 
==Notification in Swift==
 
Listen notification in swift
 
<pre class="brush:swift">
 
func tweetSent(notification: NSNotification) {
 
    let newTweet:Dictionary<String, Tweet> = notification.userInfo as Dictionary<String, Tweet>
 
}
 
NSNotificationCenter.defaultCenter().addObserver(self, selector: "tweetSent:", name: "newTweetNotification", object: nil)
 
</pre>
 
Send/Post notification in swift
 
<pre class="brush:swift">
 
var userInfo: Dictionary<String, Tweet> = ["tweet": newTweet]
 
NSNotificationCenter.defaultCenter().postNotificationName("newTweetNotification", object: nil, userInfo: userInfo)
 
</pre>
 
Remove notification observer
 
<pre class="brush:swift">
 
deinit {
 
    NSNotificationCenter.defaultCenter().removeObserver(self)
 
}
 
</pre>
 
==Get Raw Histogram from CGImage in swift==
 
Credit to http://stackoverflow.com/questions/27237297/how-to-get-meaningful-ciareahistogram-output
 
  
<pre class="brush:swift">
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==[[Swift:Auto Table Row Height]]==
//dataImage is a CGImage
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var imageData: CFDataRef = CGDataProviderCopyData(CGImageGetDataProvider(dataImage))
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==[[Swift:Navigation between storyboards]]==
var dataInput: UnsafePointer<UInt8> = CFDataGetBytePtr(imageData)
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//In swift, I have to do 2 steps. Not sure if there is any better way
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==[[Swift:Notification Observer Using NSNotificationCenter]]==
var dataInputMutable = UnsafeMutablePointer<Void>(dataInput)
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var height: vImagePixelCount = CGImageGetHeight(dataImage)
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==[[Swift:Get Raw Histogram from CGImage]]==
var width: vImagePixelCount = CGImageGetWidth(dataImage)
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//Build a vImage_Buffer for next step
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==[[Swift:UIGraphics Drawing on UIView]]==
var vImageBuffer = vImage_Buffer(data: dataInputMutable, height: height, width: width, rowBytes: CGImageGetBytesPerRow(dataImage))
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//Build the output array.
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==[[Swift:UIGraphics Scale Down CGImage]]==
//To init a multi-dimensional UnsafeMutablePointer array. I have to do 3 steps
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//First alloc sub arrays
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==[[Swift: Convert between CGImage, CIImage and UIImage]]==
var r = UnsafeMutablePointer<vImagePixelCount>.alloc(256)
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var g = UnsafeMutablePointer<vImagePixelCount>.alloc(256)
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==[[Swift:Detect Volumn Button Press]]==
var b = UnsafeMutablePointer<vImagePixelCount>.alloc(256)
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var a = UnsafeMutablePointer<vImagePixelCount>.alloc(256)
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//Then alloc main array
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var histogram = UnsafeMutablePointer<UnsafeMutablePointer<vImagePixelCount>>.alloc(4)
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//Set the pointer of sub arrays
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histogram[0] = r
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histogram[1] = g
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histogram[2] = b
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histogram[3] = a
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//Finally, do the histogram calculation
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var error:vImage_Error = vImageHistogramCalculation_ARGB8888(&vImageBuffer, histogram, 0);
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if (error == kvImageNoError) {
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    for var j = 0; j < 256; j++ {
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        let currentVal = histogram[0][j] + histogram[1][j] + histogram[2][j] //I am making a grey histogram
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        if currentVal > 0 {
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            println("j=\(j),\(currentVal)")
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        }
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    }
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    //delloc. MUST do this manually to prevent memory leak
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    r.dealloc(256)
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    g.dealloc(256)
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    b.dealloc(256)
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    a.dealloc(256)
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    histogram.dealloc(4)
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} else {
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    println("Histogram vImage error: \(error)")
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}
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</pre>
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==UIGraphics Drawing on UIView==
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===Swift: Tutorial Drawing Graphic===
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See http://www.techotopia.com/index.php/An_iOS_8_Swift_Graphics_Tutorial_using_Core_Graphics_and_Core_Image
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===Swift: How to make UIGraphics context background transparent===
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==[[Swift:NSTimer scheduledTimerWithTimeInterval]]==
If you want to set a transparent background of the content you are drawing.
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<pre class="brush:swift">
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// UIGraphics draw transparent background context
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@IBOutlet weak var histogramView: HistogramView!
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override func viewWillAppear(animated: Bool) {
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    histogramView.opaque = false
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    histogramView.backgroundColor = UIColor.clearColor()
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}
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class HistogramView: UIView {
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    override func drawRect(rect: CGRect) {
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        // draw content
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        let context = UIGraphicsGetCurrentContext()
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        CGContextClearRect(context, rect)
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    }
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}
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</pre>
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Latest revision as of 03:10, 9 April 2015

Swift Code Snippts

Back To IOS_Swift

Swift: Use NSUserDefaults to Store Persistence Data

Swift: Making Network Request Using NSURLConnection

Swift:Use AFNetworking setImageWithURL

Swift:Using UIRefreshControl

Swift:Using UIGestureRecognizer

Swift:Example of fetching messages from Parse

https://gist.github.com/sandofsky/7134b1ff90d235901254

Swift:Auto Table Row Height

Swift:Navigation between storyboards

Swift:Notification Observer Using NSNotificationCenter

Swift:Get Raw Histogram from CGImage

Swift:UIGraphics Drawing on UIView

Swift:UIGraphics Scale Down CGImage

Swift: Convert between CGImage, CIImage and UIImage

Swift:Detect Volumn Button Press

Swift:NSTimer scheduledTimerWithTimeInterval