If you write Obj-C code, you can try moving the webview a little bit.
CGRect pb = self.webView.superview.bounds, wf = self.webView.frame, bf = self.bannerView.frame;
wf.origin.y = bf.size.height;
wf.size.height = pb.size.height-wf.origin.y;
self.webView.frame = wf;
Or, you may try a mature AdMob plugin to do this. There are quite a few options.
For example:
Just use 1-2 line of javascript to show a banner or interstitla Ad.
By default, it shows the banner at top center without overlap.
var ad_units = {
ios : {
banner: 'ca-app-pub-xxx/xxx',
interstitial: 'ca-app-pub-xxx/xxx'
},
android : {
banner: 'ca-app-pub-xxx/xxx',
interstitial: 'ca-app-pub-xxx/xxx'
}
};
// select the right Ad Id according to platform
var admobid = ( /(android)/i.test(navigator.userAgent) ) ? ad_units.android : ad_units.ios;// it will display smart banner at top center, using the default options
if(AdMob) AdMob.createBanner( admobid.banner );