将最大宽度设置为约束

Question

I have rectangle with four constraints. All works ok, but on ipad this rectangle is too big. So is there a way to set max margin for constraints. i tried set Relation value to "gather then" or "less then" but it not works.

Answer 1

Constraints have a field for priority. This is a case where you want to use that. It looks like you want your rectangle to be centered, so I would recommend the following constraints:

1. CenterX of rectangle equal to CenterX of superView. Priority 1000
2. CenterY of rectangle equal to CenterY of superView. Priority 1000
3. Width of rectangle less than or equal to maximum size you want for iPad. Priority 1000
4. Height of rectangle less than or equal to maximum size you want for iPad. Priority 1000
5. Vertical constraint for distance from top of superView. Priority 750
6. Horizontal constraint for distance from leading edge of superView. Priority 750

On iPhones, all of the constraints will be met because the rectangle will easily be smaller than the maximum size for iPad.

On iPads, the higher priority width and height constraints will keep the rectangle from growing too big, and Auto Layout will allow the top and leading edge constraints to be broken to make that possible, but it will make the rectangle as big as possible to come as close as possible to meeting the horizontal and vertical offsets.