Add http:// to NSURL if it's not there

NSString *urlString = @"google.com";
NSURL *webpageUrl;

if ([urlString hasPrefix:@"http://"] || [urlString hasPrefix:@"https://"]) {
    webpageUrl = [NSURL URLWithString:urlString];
} else {
    webpageUrl = [NSURL URLWithString:[NSString stringWithFormat:@"http://%@", urlString]];
}

NSURLRequest *urlRequest = [NSURLRequest requestWithURL:webpageUrl];
[self.myWebView loadRequest:urlRequest];

Let me update answer to Swift 4 and WKWebKit

        var urlString = "www.apple.com"

    if urlString.hasPrefix("https://") || urlString.hasPrefix("http://"){
        let myURL = URL(string: urlString)
        let myRequest = URLRequest(url: myURL!)
        webView.load(myRequest)
    }else {
        let correctedURL = "http://\(urlString)"
        let myURL = URL(string: correctedURL)
        let myRequest = URLRequest(url: myURL!)
        webView.load(myRequest)
    }