I found the solution (hack) in this page
basically you just have to compare if the iOS version is bigger equals than 7 and if it does, increment the height of the toolbar.
Here is the code:
app.js
launch: function() {
// Destroy the #appLoadingIndicator element
Ext.fly('appLoadingIndicator').destroy();
// Initialize the main view
Ext.Viewport.add(Ext.create('StromRechner.view.Viewport'));
// Adjust toolbar height when running in iOS to fit with new iOS 7 style
if (Ext.os.is.iOS && Ext.os.version.major >= 7) {
Ext.select(".x-toolbar").applyStyles("height: 62px; padding-top: 15px;");
}
},