objective c - Set Autolayout Constraints Relative to Device Size -

i fell trap of relying on autolayout. have viewcontroller ton of uiviews , realized they're distorted on smaller devices (iphone 4s , 5).

is possible set constraints in autolayout relative device size.

for example, have 1 uiview several other uiviews aligned edges. change height in autolayout of 1 uiview equal half device height.

yes. there way constrain screen size.

they called size classes.

in interface builder on bar @ bottom of screen says wany hany, pulldowns. select combination of height , width of device , orientation want constrain to, , when create constraints in mode, they'll specific size/orientation. can add , modify size-specific constraints in inspector, constraint editor pane, in interface builder.

if need tweak corner case things aren't able accomplish conveniently enough size clases, can make iboutlet constraint , refer in code, , modify when view appears , changes, similar following example. easier , safer trying generate constraints scratch programmatically.

note: when modifying nslayout constraint via ib outlet, can tweak constant field, not multiplier because multiplier readonly @ runtime. whatever scaling factor use (if any) must multiplied whatever final value use constant.

@iboutlet var tableytopconstraint : nslayoutconstraint!  override func viewwillappear(animated: bool) {      adjustviewlayout(uiscreen.mainscreen().bounds.size) }  override func viewwilltransitiontosize(size: cgsize, withtransitioncoordinator coordinator: uiviewcontrollertransitioncoordinator) {         adjustviewlayout(size) }  func adjustviewlayout(size: cgsize) {     switch(size.width, size.height) {     case (320, 480):                        // iphone 4s in portrait         tableytopconstraint.constant = 0     case (480, 320):                        // iphone 4s in landscape         tableytopconstraint.constant = 0     case (320, 568):                        // iphone 5/5s in portrait         tableytopconstraint.constant = 0     case (568, 320):                        // iphone 5/5s in landscape         tableytopconstraint.constant = 0     case (375, 667):                        // iphone 6 in portrait         tableytopconstraint.constant = 0     case (667, 375):                        // iphone 6 in landscape         tableytopconstraint.constant = 0     case (414, 736):                        // iphone 6 plus in portrait         tableytopconstraint.constant = 0     case (736, 414):                        // iphone 6 plus in landscape         tableytopconstraint.constant = 0     default:         break     }     view.setneedslayout()  }