Adding constraints to a UIBarButtonItem

问题:

Xcode is not allowing me to put constraints on my BarButtonItem on a ViewController in the MainStoryBoard. It's appearing too far to the left where it's unreadable as shown in the image.

The image below shows where the BarButtonItem is. It's supposed to say "Item". I also looked on the preview split screen on Xcode and it looked fine for the iPhone6 but not for the iPhone 4 (it's half cut on the iPhone 4 but here its 3/4s cut). Here I'm running for the iPhone 6 and i get that.

How do I add constraints in Xcode or how do I add the constraints programmatically to this BarButtonItem?

Any help is much appreciated.

回答1:

Drag and drop navigation bar in your xib / story board

U can add constraints to this navigation bar as per your requirement.

Then add Bar Button Item to your navigation bar

Bar Button Item takes it default position u cannot incorporate autolayout there.

Although if u want positions of Bar Button Item Fixed or Flexible u can make use of Fixed Space Bar Button Item or Flexible Space Bar Button Item.

If positions are fixed drag Fixed Space Bar Button between your two Bar Button Item's. And if positions is not fixed its flexible drag Flexible Space Bar Button Item between your two Bar Button Item's.

Happy Coding.. :)

回答2:

Try this:

let rightConstraint = NSLayoutConstraint(item: your_item_here, attribute: .Right, relatedBy: .Equal, toItem: your_item_here, attribute: .Left, multiplier: 0, constant: 1)
your_item_here.addConstraint(rightConstraint)

P.S if you want to add constraint to your UIBarButtonItem, it will rise an error

Value of type 'UIBarButtonItem' has no member 'addConstraint'

P.S.S

Because of it is not a view class, you can't apply constraints to it.