CODEWITHSUNDEEP
iosxcodeswift
alex
alex

Reputation: 1774

Unable to simultaneously satisfy constraints - Swift

Summary: I just got finished doing auto-layout and when I run it, it is all scrunched together. Then I look at the command prompt and it says the error above. I've tried googling it but it just shows solutions for Obj-C and I'm doing it in Swift. How would I be able to solve this auto-layout issue?

Error:

2014-10-20 00:07:41.102 Fraction Calculator[74247:6698760] 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:0x7c440f10 V:[UIButton:0x7c440db0'Divide It!'(30)]>",
    "<NSLayoutConstraint:0x7af7bdb0 V:[UIImageView:0x7af7bae0(8)]>",
    "<NSLayoutConstraint:0x7ae928b0 V:[UITextField:0x7ae952d0(30)]>",
    "<NSLayoutConstraint:0x7ae97110 V:[UITextField:0x7ae96f70(30)]>",
    "<NSLayoutConstraint:0x7ae97eb0 V:[UILabel:0x7ae97d70'Enter Your Fraction To Be...'(48)]>",
    "<NSLayoutConstraint:0x7ae99cd0 V:[_UILayoutGuide:0x7ae990c0]-(0)-[UILabel:0x7ae97d70'Enter Your Fraction To Be...']>",
    "<NSLayoutConstraint:0x7ae9a000 V:[UILabel:0x7ae97d70'Enter Your Fraction To Be...']-(41)-[UITextField:0x7ae96f70]>",
    "<NSLayoutConstraint:0x7ae9a090 V:[UITextField:0x7ae96f70]-(14)-[UIImageView:0x7af7bae0]>",
    "<NSLayoutConstraint:0x7ae9a150 V:[UIImageView:0x7af7bae0]-(13)-[UITextField:0x7ae952d0]>",
    "<NSLayoutConstraint:0x7ae9a270 V:[UITextField:0x7ae952d0]-(59)-[UIButton:0x7c440db0'Divide It!']>",
    "<NSLayoutConstraint:0x7ae9a2a0 V:[UIButton:0x7c440db0'Divide It!']-(50)-[UILabel:0x7ae98df0]>",
    "<NSLayoutConstraint:0x7ae9a300 V:[UILabel:0x7ae98df0]-(166)-[_UILayoutGuide:0x7ae99680]>",
    "<_UILayoutSupportConstraint:0x7c441e80 V:[_UILayoutGuide:0x7ae990c0(20)]>",
    "<_UILayoutSupportConstraint:0x7c441770 V:|-(0)-[_UILayoutGuide:0x7ae990c0]   (Names: '|':UIView:0x7af7abc0 )>",
    "<_UILayoutSupportConstraint:0x7c443610 V:[_UILayoutGuide:0x7ae99680(0)]>",
    "<_UILayoutSupportConstraint:0x7c4429d0 _UILayoutGuide:0x7ae99680.bottom == UIView:0x7af7abc0.bottom>",
    "<NSLayoutConstraint:0x7c44acf0 'UIView-Encapsulated-Layout-Height' V:[UIView:0x7af7abc0(480)]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x7ae97eb0 V:[UILabel:0x7ae97d70'Enter Your Fraction To Be...'(48)]>

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.

An Image of My Constraints https://www.dropbox.com/s/1l3ys9k7bdr8qrk/Screenshot%202014-10-20%2021.08.47.png?dl=0 An image of my iPhone 4 Preview https://www.dropbox.com/s/7uoulzppalex2r8/Screenshot%202014-10-20%2021.09.48.png?dl=0 Image of the iPhone 4 in the Simulator https://www.dropbox.com/s/c1qedgoytcnetri/iOS%20Simulator%20Screen%20Shot%20Oct%2020%2C%202014%2C%209.10.03%20PM.png?dl=0

If you guys have questions or need clarification please comment down below

Upvotes: 2

Views: 12913

Answers (2)

TheRealRonDez
TheRealRonDez

Reputation: 2807

I had a hard time figuring out what constraints were causing this error. Here is a simpler way to do it.

I'm using Xcode 6.1.1

"Command + A" to select all the UILabels, UIImages etc. Click Editor -> Pin > (Select...) to Superview again click Editor -> Resolve Auto Layout Issues -> Add Missing Constraints or Reset to Suggested Constraints. It depends on your case.

Upvotes: 2

akshaynhegde
akshaynhegde

Reputation: 1938

It would be a bit hard to track which is the bad constraint by just looking at the error you have posted. But I can give a general rules or things to keep in mind while working with autolayout or constraints in general,

  • Prefer setting constraints in XIB/Storyboards. It will tell where exactly are you going wrong right when you are setting them. You can almost do everything in the interface builder unless its a special case.
  • Always set constraints in relative to views around it try not fix everything to super View
  • Use aspect ratio constraints whenever possible.
  • Try to use Intrinsic constraint sizes of views and avoid setting fixed widths/heights.
  • Remember you will always get into the kind of errors you are facing, when you set too many constraints. So always think are the constraints "just enough" to figure out its frame in run time. Not more or less but just enough.
  • Make use of in-equality constraints, they are very helpful. Also don't forget you have hugging Priorities and compression resistance priorities.

In your error, I see a lot of constraints which have fixed sizes, they would interfere when you have spacing constraint to those views. So start for the first, and keep the points I mentioned and delete the constraints you don't need.

References,

Upvotes: 6

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