Difference between revisions of "Swift code snippets"
From Hawk Wiki
m (→Notification in Swift) |
(→Notification in Swift) |
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deinit { | deinit { | ||
NSNotificationCenter.defaultCenter().removeObserver(self) | 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"> | ||
+ | //dataImage is a CGImage | ||
+ | var imageData: CFDataRef = CGDataProviderCopyData(CGImageGetDataProvider(dataImage)) | ||
+ | var dataInput: UnsafePointer<UInt8> = CFDataGetBytePtr(imageData) | ||
+ | //In swift, I have to do 2 steps. Not sure if there is any better way | ||
+ | var dataInputMutable = UnsafeMutablePointer<Void>(dataInput) | ||
+ | var height: vImagePixelCount = CGImageGetHeight(dataImage) | ||
+ | var width: vImagePixelCount = CGImageGetWidth(dataImage) | ||
+ | //Build a vImage_Buffer for next step | ||
+ | var vImageBuffer = vImage_Buffer(data: dataInputMutable, height: height, width: width, rowBytes: CGImageGetBytesPerRow(dataImage)) | ||
+ | //Build the output array. | ||
+ | //To init a multi-dimensional UnsafeMutablePointer array. I have to do 3 steps | ||
+ | //First alloc sub arrays | ||
+ | var r = UnsafeMutablePointer<vImagePixelCount>.alloc(256) | ||
+ | var g = UnsafeMutablePointer<vImagePixelCount>.alloc(256) | ||
+ | var b = UnsafeMutablePointer<vImagePixelCount>.alloc(256) | ||
+ | var a = UnsafeMutablePointer<vImagePixelCount>.alloc(256) | ||
+ | //Then alloc main array | ||
+ | var histogram = UnsafeMutablePointer<UnsafeMutablePointer<vImagePixelCount>>.alloc(4) | ||
+ | //Set the pointer of sub arrays | ||
+ | histogram[0] = r | ||
+ | histogram[1] = g | ||
+ | histogram[2] = b | ||
+ | histogram[3] = a | ||
+ | //Finally, do the histogram calculation | ||
+ | var error:vImage_Error = vImageHistogramCalculation_ARGB8888(&vImageBuffer, histogram, 0); | ||
+ | |||
+ | if (error == kvImageNoError) { | ||
+ | for var j = 0; j < 256; j++ { | ||
+ | let currentVal = histogram[0][j] + histogram[1][j] + histogram[2][j] //I am making a grey histogram | ||
+ | if currentVal > 0 { | ||
+ | println("j=\(j),\(currentVal)") | ||
+ | } | ||
+ | } | ||
+ | //delloc. MUST do this manually to prevent memory leak | ||
+ | r.dealloc(256) | ||
+ | g.dealloc(256) | ||
+ | b.dealloc(256) | ||
+ | a.dealloc(256) | ||
+ | histogram.dealloc(4) | ||
+ | } else { | ||
+ | println("Histogram vImage error: \(error)") | ||
} | } | ||
</pre> | </pre> |
Revision as of 06:21, 19 March 2015
Contents
Swift Code snippts
Back To IOS_Swift
Making Network Request
var clientId = "Put your client id here" var url = NSURL(string: "https://api.instagram.com/v1/media/popular?client_id=\(clientId)")! var request = NSURLRequest(URL: url) NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue()) { (response: NSURLResponse!, data: NSData!, error: NSError!) -> Void in var responseDictionary = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: nil) as NSDictionary self.photos = responseDictionary["data"] as NSArray self.tableView.reloadData() println("response: \(self.photos)") }
Use AFNetworking setImageWithURL
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.
In an Objective-C bridging file:
#import <AFNetworking/UIImageView+AFNetworking.h>
In the swift view file, to set a imageView using URL:
setImageWithURL(NSURL(string: thumbnailURL))
Adding UIRefreshControl
//refreshControl is automatically defined in UITableViewController var refreshControl: UIRefreshControl? override func viewDidLoad() { super.viewDidLoad() refreshControl = UIRefreshControl() refreshControl?.addTarget(self, action: "fetch", forControlEvents: UIControlEvents.ValueChanged) tableView.insertSubview(refreshControl!, atIndex: 0) } //to stop refresh, call if let rc = self.refreshControl { self.refreshControl!.endRefreshing() }
Example of fetching messages from Parse
https://gist.github.com/sandofsky/7134b1ff90d235901254
Auto Table Row Height
//Auto table row height tableView.estimatedRowHeight = 92.0 tableView.rowHeight = UITableViewAutomaticDimension
var vc = storyboard.instantiateViewControllerWithIdentifier("loginViewController") as UIViewController window?.rootViewController = vc
First, drag a segue in storyboard and give it an identifier, then in the button action (or any action you like), do:
self.performSegueWithIdentifier("loginSegue", sender: self)
Sometimes, you want to access the UIViewController from a navigation controller
var vc = storyboard?.instantiateViewControllerWithIdentifier("navigationID") as UINavigationController var v = vc.viewControllers[0] as ViewController // [0] represents the first level UIViewController under NavigationController
Notification in Swift
Listen notification in 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)
Send/Post notification in swift
var userInfo: Dictionary<String, Tweet> = ["tweet": newTweet] NSNotificationCenter.defaultCenter().postNotificationName("newTweetNotification", object: nil, userInfo: userInfo)
Remove notification observer
deinit { NSNotificationCenter.defaultCenter().removeObserver(self) }
Get Raw Histogram from CGImage in swift
Credit to http://stackoverflow.com/questions/27237297/how-to-get-meaningful-ciareahistogram-output
//dataImage is a CGImage var imageData: CFDataRef = CGDataProviderCopyData(CGImageGetDataProvider(dataImage)) var dataInput: UnsafePointer<UInt8> = CFDataGetBytePtr(imageData) //In swift, I have to do 2 steps. Not sure if there is any better way var dataInputMutable = UnsafeMutablePointer<Void>(dataInput) var height: vImagePixelCount = CGImageGetHeight(dataImage) var width: vImagePixelCount = CGImageGetWidth(dataImage) //Build a vImage_Buffer for next step var vImageBuffer = vImage_Buffer(data: dataInputMutable, height: height, width: width, rowBytes: CGImageGetBytesPerRow(dataImage)) //Build the output array. //To init a multi-dimensional UnsafeMutablePointer array. I have to do 3 steps //First alloc sub arrays var r = UnsafeMutablePointer<vImagePixelCount>.alloc(256) var g = UnsafeMutablePointer<vImagePixelCount>.alloc(256) var b = UnsafeMutablePointer<vImagePixelCount>.alloc(256) var a = UnsafeMutablePointer<vImagePixelCount>.alloc(256) //Then alloc main array var histogram = UnsafeMutablePointer<UnsafeMutablePointer<vImagePixelCount>>.alloc(4) //Set the pointer of sub arrays histogram[0] = r histogram[1] = g histogram[2] = b histogram[3] = a //Finally, do the histogram calculation var error:vImage_Error = vImageHistogramCalculation_ARGB8888(&vImageBuffer, histogram, 0); if (error == kvImageNoError) { for var j = 0; j < 256; j++ { let currentVal = histogram[0][j] + histogram[1][j] + histogram[2][j] //I am making a grey histogram if currentVal > 0 { println("j=\(j),\(currentVal)") } } //delloc. MUST do this manually to prevent memory leak r.dealloc(256) g.dealloc(256) b.dealloc(256) a.dealloc(256) histogram.dealloc(4) } else { println("Histogram vImage error: \(error)") }