Unity mobile development tools

Hello guys, I have a situation and gonna need your advice. Short history: I work for a company that writes mobile apps using the cross platform capabilities of Unity. Now we are working on an IOS app project that has been changing visual END design for half a year. The customer cannot determine the final version of the application. As a result, our application mired in legacy code and in various "crutches". Basically 80% of the application consists of a UI but it was supposed to have games in it, that was another reason to choose Unity as the development environment. We do not have the standards of mobile applications because we use absolutely not suitable tool. The question is, maybe someone knows the tools that can facilitate the development of IOS (ofc it would be great for Android too) applications on Unity? How can we get closer to Xamarin? Because the addition of native IOS alert took about 3 days of development, as it was necessary to work smoothly with Object-C developer and then how to connect our code with it. Let's say such a new feature that Apple offers in the new IOS 12 is not at all for us. To implement even the simplest feature, we will spend a lot of resources. The question is, does anyone have or had a similar experience? And can recommend tools that make it easier to develop IOS and Android applications? Paid or free. Maybe some of the tools of Unity itself which is in the pro but not in the personal version? Mostly interested in convenient layout since most of the tasks fall on the design change, (the customer does not like the prototypes) as a result, we are unity developers are engaged in more design (popup, buttons, media management, F.X. like blure windows etc.). Any suggestions colleagues?,Hello guys, i have a situation and gonna need your advice. Short history: I work for a company that writes mobile apps using the cross platform capabilities of Unity. Now we are working on an IOS app project that has been changing visual END design for half a year already. The customer cannot determine the final version of the application. As a result, our application mired in legacy code and in various "crutches". Basically 80% of the application consists of a UI but it was supposed to have games, that btw was another reason to choose Unity as the development environment. We do not have the standards of mobile applications because we use absolutely not suitable tool. The question is, maybe someone knows the tools that can facilitate the development of IOS applications on Unity? How can we get closer to Xamarin? Because the addition of native IOS alert took about 3 days of development, as it was necessary to work smoothly with Object-C developer and then how to connect our code with it. Let's say such a new feature that Apple offers in the new IOS 12 is not at all for us. To implement even the simplest feature, we will spend a lot of resources. The question is, does anyone have or had a similar experience? And can recommend tools that make it easier to develop IOS and Android applications? Paid or free. Maybe some of the tools of Unity itself which is in the pro but not in the personal version? Mostly interested in convenient layout since most of the tasks fall on the design change, (the customer does not like the prototypes) as a result, we are unity developers are engaged in more design (popup, buttons, media management, F.X. like blure windows etc.). Any suggestions colleagues?