Difficulty 2: How to make reasonable use of screen space
It is difficult to effectively use the screen space for the selection menu. For example, Country Email List the display list style that comes with the system in iOS9 only occupies 50% of the screen space, which also leads to users only viewing and operating in this 50% space.
Assuming the groups of options come from the same context, and regardless of how the groups of options relate to each other, you might consider using the following controls instead of drop-down lists:
1) Utilize a set of radio buttons or split options to display options of similar type but independent of each other (e.g. select region, Figure 10)
Figure 10, Radio Group
2) A digital stepper, which can be used on options that can only increment/decrement their number, to allow the user to easily fine-tune the value (eg select the number of passengers, Figure 11)
Figure 11, Stepper
3) State switcher, which can be used to quickly switch between two opposite states (Fig. 12)
Figure 12, Switcher
4) Slide the controller to smoothly control the value and inform the optional range (Figure 13)
Figure 13, Slider
When you need to design a more complex drop-down selection form, first look at each question and the characteristics of the options it contains, and consider which form of interaction is more suitable.
Remember one common principle when designing selection menus - you must minimize unnecessary typing. In some cases, multiple selection menus can even be condensed into a single input control, thereby simplifying the interaction flow and greatly reducing the cognitive load on the user in understanding selection operations.
Selection menus often expose many design problems, such as lack of necessary guidance for filling in, hiding options when unnecessary, and only providing choices but not allowing users to modify them.
But that doesn't mean you should avoid them in interface design. The reason why selection menus are prone to so many problems is that designers don't use them in the right way in the right situation.
What exactly makes design good and bad?