Change Spacing Between UIBarButtonItems in iOS 8

问题:

I have a UINavigationItem on my view controller, and I am trying to reduce the spacing between my two RightBarButtonItems. Here is some of my code:

// Create two UIBarButtonItems
    let item1:UIBarButtonItem = UIBarButtonItem(customView: view1)
    let item2:UIBarButtonItem = UIBarButtonItem(customView: view2)

    var fixedSpace:UIBarButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FixedSpace, target: nil, action: nil)
    fixedSpace.width = -20.0

    // Add the rightBarButtonItems on the navigation bar
    viewController.navigationItem.rightBarButtonItems = [item2, fixedSpace, item1]

As can be seen, I am using a FixedSpace UIBarButtonItem, but this is not changing the spacing for some reason. I have thought about subclassing either the UINavigationItem or the UIBarButtonItem so that I can set the spacing accordingly, but I couldn't seem to find any methods that I could override to change the spacing between items.

Any insight on how to solve this problem would be greatly appreciated!

回答1:

Thanks to @Fogmeister's help, I figured out that the width of the view1 and view2 objects, which are UIButtons, was too large. That was why there was abnormal spacing between them. Here is my final code:

// Get the first button's image
    var view1Img:UIImage = UIImage(named: "Image1")!

    // Create the first button
    var view1:UIButton = UIButton(frame: CGRect(x: 0, y: 0, width: view1Img.size.width, height: view1Img.size.height))

    // Get the second button's image
    var view2Img:UIImage = UIImage(named: "Image2")!

    // Create the second button
    var view2:UIButton = UIButton(frame: CGRect(x: 0, y: 0, width: view2Img.size.width, height: view2Img.size.height))

    // Create two UIBarButtonItems
    let item1:UIBarButtonItem = UIBarButtonItem(customView: view1)
    let item2:UIBarButtonItem = UIBarButtonItem(customView: view2)

    // Set 26px of fixed space between the two UIBarButtonItems
    var fixedSpace:UIBarButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FixedSpace, target: nil, action: nil)
    fixedSpace.width = 26.0

    // Set -7px of fixed space before the two UIBarButtonItems so that they are aligned to the edge
    var negativeSpace:UIBarButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FixedSpace, target: nil, action: nil)
    negativeSpace.width = -7.0

    // Add the rightBarButtonItems on the navigation bar
    viewController.navigationItem.rightBarButtonItems = [negativeSpace, item2, fixedSpace, item1]

I create the background image for the first UIButton and then use its size to create the frame for that UIButton. I perform the same actions for the second UIButton. Then, I create UIBarButtonItems from the two UIButtons. After that, I create 26px of fixed space and then -7.0px of fixed space. The purpose of the former is to create a certain amount of space between the two buttons. The purpose of the latter is to move all UIBarButtonItems over to the right. Then, I add all of the UIBarButtonItems as rightBarButtonItems in a particular order so I get the look that I want.

It works great now! Thanks for all of the help, Fogmeister!

回答2:

Another way is just by changing the Left and Right Image Inset in IB.

回答3:

From the docs for UIBarButtonItem...

If the value is 0.0 or negative, the item sets the width of the combined image and title to fit.

If you set the width to -20.0 it will ignore it and use the standard width.

What is it you are trying to achieve with a negative width anyway? I'm almost certain there will be a better way.