I'm practicing Webkit in swift. I'm following this tutorial for the same purpose. And I'm stuck with an error in the very first few lines of the code.
This is what I have in the ViewController.swift so far :
import UIKit
import WebKit
class ViewController: UIViewController {
var webView : WKWebView
required init(coder aDecoder: NSCoder) {
self.webView = WKWebView(frame: CGRectZero)
super.init(coder: aDecoder)!
}
override func viewDidLoad() {
super.viewDidLoad()
self.view.addSubview(webView)
webView.translatesAutoresizingMaskIntoConstraints = false
let height = NSLayoutConstraint(item: webView, attribute: .Height, relatedBy: .Equal, toItem: view, attribute: .Height, multiplier: 1, constant: 0)
let width = NSLayoutConstraint(item: webView, attribute: .Width, relatedBy: .Equal, toItem: view, attribute: .Width, multiplier: 1, constant: 0)
webView.addConstraints([height,width])
let url = NSURL(string: "http://www.google.com")
let urlRequest = NSURLRequest(URL: url!)
webView.loadRequest(urlRequest)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
}
and the following is how the console error output looks:
2016-10-27 11:29:09.015 Browser[68308:1113663] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '***
+[NSLayoutConstraint constraintWithItem:attribute:relatedBy:toItem:attribute:multiplier:constant:]: Constraint items must each be an instance of UIView, or NSLayoutGuide.'
*** First throw call stack: ( 0 CoreFoundation 0x00000001060e0d85 __exceptionPreprocess + 165 1 libobjc.A.dylib 0x0000000108486deb objc_exception_throw + 48 2 CoreFoundation 0x00000001060e0cbd +[NSException raise:format:] + 205 3 Foundation 0x00000001064af0ac +[NSLayoutConstraint constraintWithItem:attribute:relatedBy:toItem:attribute:multiplier:constant:]
+ 277 4 Browser 0x0000000105ef890b _TTOFCSo18NSLayoutConstraintCfT4itemPs9AnyObject_9attributeOSC17NSLayoutAttribute9relatedByOSC16NSLayoutRelation6toItemGSqPS0___9attributeS1_10multiplierV12CoreGraphics7CGFloat8constantS4__S_
+ 123 5 Browser 0x0000000105ef78ee _TFC7Browser14ViewController11viewDidLoadfT_T_ + 494 6 Browser 0x0000000105ef7c12 _TToFC7Browser14ViewController11viewDidLoadfT_T_ + 34 7 UIKit 0x0000000106aa5984
-[UIViewController loadViewIfRequired] + 1198 8 UIKit 0x0000000106aa5cd3 -[UIViewController view] + 27 9 UIKit 0x000000010697bfb4 -[UIWindow addRootViewControllerViewIfPossible] + 61 10 UIKit 0x000000010697c69d
-[UIWindow _setHidden:forced:] + 282 11 UIKit 0x000000010698e180 -[UIWindow makeKeyAndVisible] + 42 12 UIKit 0x0000000106902ed9 -[UIApplication
_callInitializationDelegatesForMainScene:transitionContext:] + 4131 13 UIKit 0x0000000106909568
-[UIApplication _runWithMainScene:transitionContext:completion:] + 1769 14 UIKit 0x0000000106906714
-[UIApplication workspaceDidEndTransaction:] + 188 15 FrontBoardServices 0x000000010a3558c8
__FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__ + 24 16 FrontBoardServices 0x000000010a355741
-[FBSSerialQueue _performNext] + 178 17 FrontBoardServices 0x000000010a355aca -[FBSSerialQueue _performNextFromRunLoopSource] + 45 18 CoreFoundation 0x0000000106006301
__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17 19 CoreFoundation 0x0000000105ffc22c
__CFRunLoopDoSources0 + 556 20 CoreFoundation 0x0000000105ffb6e3 __CFRunLoopRun + 867 21 CoreFoundation 0x0000000105ffb0f8 CFRunLoopRunSpecific + 488 22 UIKit 0x0000000106905f21 -[UIApplication _run] + 402 23 UIKit 0x000000010690af09 UIApplicationMain + 171 24 Browser 0x0000000105ef92f2 main + 114 25 libdyld.dylib 0x0000000108f5d92d start + 1 ) libc++abi.dylib: terminating with uncaught exception of type NSException
I'm a beginner so needless to say, I don't have any idea what this means.
Additionally I'm getting the error message
Thread 1: signal SIGABRT which I normally get if I ignore to remove an outlet reference that I created earlier. In this case I have not created any outlets.
I've gone through some other answers on Stack on similar problems in Objective C but I couldn't understand it well.
I know the solution might be relatively simple but any help will be appreciated.
So I finally fixed the code! Here's the corrected code.
import UIKit
import WebKit
class ViewController: UIViewController {
var webView : WKWebView
required init(coder aDecoder: NSCoder) {
self.webView = WKWebView(frame: CGRect(x: 0, y: 0, width: 414, height: 736))
super.init(coder: aDecoder)!
}
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(webView)
webView.translatesAutoresizingMaskIntoConstraints = false
let views = ["webView" : webView]
let h = NSLayoutConstraint.constraintsWithVisualFormat("H:|[webView]|", options: [], metrics: nil , views: views)
let w = NSLayoutConstraint.constraintsWithVisualFormat("V:|[webView]|", options: [], metrics: nil, views: views)
view.addConstraints(h) //This is where I was going wrong
view.addConstraints(w) //This is where I was going wrong
let url = NSURL(string: "http://www.google.com")
let urlRequest = NSURLRequest(URL: url!)
webView.loadRequest(urlRequest)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
Turns out I was adding the constraints to webView where I should have been adding it to view.