How to add constraints programmatically using Swift

Question

I\'m trying to figure this out since last week without going any step further. Ok, so I need to apply some constraints programmatically

Answer 1

Would like to add some theoretical concept to Imanou Petit’s answer, so that one can understand how auto layout works.

To understand auto layout consider your view as rubber's object which is shrinked initially.

To place an object on screen we need 4 mandatory things :

• X coordinate of object (horizontal position).

• Y coordinate of object (vertical position )

• Object’s Width

• Object’s Height.

1 X coordinate: There are multiple ways of giving x coordinates to a view.

Such as Leading constraint, Trailing constraint , Horizontally centre etc.

2 Y coordinate: There are multiple ways of giving y coordinates to a view :

Such as Top constraint, Bottom constraint , Vertical centre etc.

3 Object's width: There are two ways of giving width constrain to a view :

a. Add fixed width constraint (consider this constraint as iron rod of fixed width and you have hooked your rubber’s object horizontally with it so rubber’s object don’t shrink or expand)

b. Do not add any width constraint but add x coordinate constraint to both end of view trailing and leading, these two constraints will expand/shrink your rubber’s object by pulling/pushing it from both end, leading and trailing.

4 Object's height: Similar to width, there are two ways of giving height constraint to a view as well :

a. Add fixed height constraint (consider this constraints as iron rod of fixed height and you have hooked your rubber’s object vertically with it so rubber’s object don’t shrink or expand)

b. Do not add any height constraint but add x coordinate constraint to both end of view top and bottom, these two constraints will expand/shrink your rubber’s object pulling/pushing it from both end, top and bottom.