Your First Swift 4 & iOS 11 App - Part 40: | Ray Wenderlich

🎓 Courses & Articles
1

Learn how to style buttons to use custom images, and style sliders to use custom thumb images.

This is a companion discussion topic for the original entry at https://www.raywenderlich.com/3990-your-first-swift-4-ios-11-app/lessons/40
3

Hi Ray,

thanks for putting together the videos - they are really helpful. I have a minor issue with this one: When doing:

let thumbImageNormal: UIImage = UIImage(named: "SliderThumb-Normal")

Xcode complains because UIImage(named:) seems to return an optional that’s not getting unwrapped. I’ve added a “!” to unwrap the optional but I’m wondering why in the video there isn’t an error while I got one.

Thanks

Lucas

4

Good question! The difference is you explicitly declared the variable as a UIImage:

let thumbImageNormal: UIImage =  ...

Whereas in the video I declare the type implicitly:

let thumbImageNormal = ...

It turns out that UIImage(named: "SliderThumb-Normal") returns an UIImage?, not a UIIImage. So my thumbImageNormal is a UIImage? while you declared yours as a UIImage.

You’ll learn a lot more about optionals and how they work in the Programming in Swift course, so keep an eye out for that :]

5

Also having issues here, my sliders don’t look the same as yours, here is my code vs yours, can anyone see the difference?

        <<<<<<<<< Mine HERE >>>>>>>>
        let thumbImageNormal = UIImage(named: "SliderThumb-Normal")
        slider.setThumbImage(thumbImageNormal, for: .normal)
        
        let thumbImageHighlighted = UIImage(named: "SliderThumb-Highlighted")
        slider.setThumbImage(thumbImageHighlighted , for: .highlighted)
        
        let insets = UIEdgeInsets(top: 0, left: 14, bottom: 0, right: 14)
        
        let trackLeftImage = UIImage(named: "SliderTrackLeft")
        let trackLeftResizable = trackLeftImage?.resizableImage(withCapInsets: insets)
        slider.setMinimumTrackImage(trackLeftResizable, for: .normal)
        
        let trackRightImage = UIImage(named: "SliderTrackRight")
        let trackRightResizable = trackRightImage?.resizableImage(withCapInsets: insets)
        slider.setMinimumTrackImage(trackRightResizable, for: .highlighted)
 */
        
//        >>>>>>>>>>>>>>>>>> yours HERE <<<<<<<<<<<<<<<<<<<<<
        
        
        let thumbImageNormal = UIImage(named: "SliderThumb-Normal")
        slider.setThumbImage(thumbImageNormal, for: .normal)
        
        let thumbImageHighlighted = UIImage(named: "SliderThumb-Highlighted")
        slider.setThumbImage(thumbImageHighlighted, for: .highlighted)
        
        let insets = UIEdgeInsets(top: 0, left: 14, bottom: 0, right: 14)
        
        let trackLeftImage = UIImage(named: "SliderTrackLeft")
        let trackLeftResizable = trackLeftImage?.resizableImage(withCapInsets: insets)
        slider.setMinimumTrackImage(trackLeftResizable, for: .normal)
        
        let trackRightImage = UIImage(named: "SliderTrackRight")
        let trackRightResizable = trackRightImage?.resizableImage(withCapInsets: insets)
        slider.setMaximumTrackImage(trackRightResizable, for: .normal)
6

apart from setMaximumTrackImage and setMinimumTrackImage I can’t see anything else wrong…

7

In yours it looks like you call setMinimumTrackImage() twice, but in mine I call setMinimumTrackImage() for the left image, and setMaximumTrackImage() for the right image. Maybe that is the issue?

8

Hi Ray

I noticed that and changed it, but there must be an other bug as it still didn’t work. I copied and pasted your code into the project to be able to keep following along.

9

This topic was automatically closed after 166 days. New replies are no longer allowed.

11

Hi I have a problem with this part of the course. See the screenshot I made.

42
421938Ă—682 129 KB

For some reason when I type “slider.setThumbImage” xcode does not auto compleet and it looks like it’s not recognized. Also I have a lot of errors. I tried to copy and past in the code of Ray but this gives the same result. Can someone give me some help?

12

I’ll found the error in a few minutes today. It was a missing “}” I suppose it wat to late yesterday and I was tired after a day of work.