Using UIActivityIndicatorView with UIWebView in Sw

问题:

I'm trying to display an Activity Indicator View in my app to users while a url is being loaded into a WebView. I've tried toying with activity.startAnimating/activity.stopAnimating and tried placing them in functions, etc. but have not had any luck.

The best I have been able to get is the Activity Indicator to appear and animate, but then not stop animating or hide once my url is loaded, so it continues spinning on top of the web page.

In other situations, when trying to move around activity.startAnimating, I have encountered the "Thread 1: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)" issue. I have "Hides when Stopped" checked in the attributes inspector, I know that my url is valid, and I have created IBOutlets for the Interface Builder Elements.

Bear with me; I'm relatively new to Swift. Here's my code:

class HighchartsController: UIViewController {

@IBOutlet weak var HighchartsView: UIWebView!

@IBOutlet weak var activity: UIActivityIndicatorView!

@IBOutlet weak var saveButton: UIBarButtonItem!

@IBOutlet weak var highchartsMenu: UIBarButtonItem!

override func viewDidLoad()
{
    super.viewDidLoad()

    if self.revealViewController() != nil {
        highchartsMenu.target = self.revealViewController()
        highchartsMenu.action = "revealToggle:"

        loadAddress()
    }
 }

func loadAddress() {

    let url = NSURL (string: "http://google.com/flights")
    let request = NSURLRequest (URL: url!)
    HighchartsView.loadRequest(request)
    println("Webpage Loaded Successfully")
 }
}

And I have tried using different functions such as

webViewDidStartLoad(_ :UIWebView){

    activity.startAnimating()
    NSLog("Webview load has started")

}
webViewDidFinishLoad(_ :UIWebView){

    activity.stopAnimating()
    NSLog("Webview load had finished")

}

回答1:

First of all, i don't see delegation of UIWebView. Realize your behaviour related to delegation processes.

UIWebViewDelegate has four methods, but use for this way just three:

Swift 4

func webViewDidStartLoad(_ webView: UIWebView) // show indicator    
func webViewDidFinishLoad(_ webView: UIWebView) // hide indicator
func webView(_ webView: UIWebView, didFailLoadWithError error: Error) // hide indicator

Swift 3

func webViewDidStartLoad(webView: UIWebView!) // show indicator
func webViewDidFinishLoad(webView: UIWebView!) // hide indicator
func webView(webView: UIWebView!, didFailLoadWithError error: NSError!) // hide indicator

回答2:

You need to add UIWebViewDelegate to your class like so.

class HighchartsController: UIViewController, UIWebViewDelegate {

You will also need to assign your webView delegate to self in viewDidLoad function like so.

HighchartsView.delegate = self

回答3:

I'm sure you figured it out by now but you need to wire up your UIWebView to set its delegate as your UIViewController in the storyboard by control-dragging.

回答4:

The following are three simple steps that I always follow in Xcode 8 / Swift 3 / iOS 10 in order to implement UIWebView page loading indicator:

Step 1. Create outlets for the Web View and Load Indicator in the ViewController class. For example:

@IBOutlet var loadSpinner: UIActivityIndicatorView!
@IBOutlet weak var webView: UIWebView!

These two lines should have non-empty dots to the left of them.

Step 2. In the Storyboard: Control-drag the WebView to the ViewController and choose "delegate" from the menu. As GarySabo correctly pointed out, without this step, the indicator will appear but won't work!

Step 3. Add the following code to your ViewController class:

func webViewDidStartLoad(_ : UIWebView) {
    loadSpinner.startAnimating()
}

func webViewDidFinishLoad(_ : UIWebView) {
    loadSpinner.stopAnimating()
}

回答5:

*WKWebView equivalent of dimpiax answer. Use WKNavigationDelegate

func webView(_ webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation!) // show indicator 

func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!)  // hide indicator 

func webView(_ webView: WKWebView, didFail navigation: WKNavigation!, withError error: Error)  // hide indicator*