How to reposition view using swift in iOS? - ios

Question

I am using story board to build ui for my application and uses swift & i have prepared below layout you can see in screen shot.
I want to hide view containing details of stop1 & place stop2 view in place of stop1 at runtime.
I am using following code to hide stop1 & update constraint of stop2
stop1Frame.hidden = true
stop2Frame.updateConstraints()
Please help me.
putting height constraint to 0 of stop1 worked but shows me below error in console.
2015-03-13 17:03:52.738 GroundSpan[5392:1777378] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
"<NSLayoutConstraint:0x7a644500 V:[UILabel:0x7a643d50'Please tap on + button to...'(63)]>",
"<NSLayoutConstraint:0x7a64cb80 V:[UIView:0x7a63aaa0(0)]>",
"<NSLayoutConstraint:0x7a64cc10 UILabel:0x7a632e20'Stop1'.top == UIView:0x7a63aaa0.topMargin>",
"<NSLayoutConstraint:0x7a64d2b0 V:[UILabel:0x7a643d50'Please tap on + button to...']-(20)-| (Names: '|':UIView:0x7a63aaa0 )>",
"<NSLayoutConstraint:0x7a64d310 V:[UILabel:0x7a632e20'Stop1']-(NSSpace(8))-[UILabel:0x7a643d50'Please tap on + button to...']>")
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x7a644500 V:[UILabel:0x7a643d50'Please tap on + button to...'(63)]>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2015-03-13 17:03:52.739 GroundSpan[5392:1777378] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
"<NSLayoutConstraint:0x7a64cb80 V:[UIView:0x7a63aaa0(0)]>",
"<NSLayoutConstraint:0x7a64cc10 UILabel:0x7a632e20'Stop1'.top == UIView:0x7a63aaa0.topMargin>",
"<NSLayoutConstraint:0x7a64d2b0 V:[UILabel:0x7a643d50'Please tap on + button to...']-(20)-| (Names: '|':UIView:0x7a63aaa0 )>",
"<NSLayoutConstraint:0x7a64d310 V:[UILabel:0x7a632e20'Stop1']-(NSSpace(8))-[UILabel:0x7a643d50'Please tap on + button to...']>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x7a64d310 V:[UILabel:0x7a632e20'Stop1']-(NSSpace(8))-[UILabel:0x7a643d50'Please tap on + button to...']>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.

Answer 1

Create an IBOutlet to the height constraint of stop1 so you can access it in your code.
To hide stop1, set its height constraint to 0, so stop2 will move up.
#IBOutlet weak var stop1HeightConstraint: NSLayoutConstraint!
...
// in your function:
self.stop1HeightConstraint.constant = 0
UIView.animateWithDuration(0.4, animations: {
self.view.layoutIfNeeded()
})
This all assumes that you have setup your autolayout and constraints correctly.