CP469 Lesson 01: Intro to XCode

Code upgrade

In attempting to replicate the demonstration app from this lesson, I ran across a piece of code which did not seem to be allowable; I’m guessing that this may be because my version of XCode is 12.3, rather than 12.2 as in the instructor’s demonstration.

    // Lecture example in class had:
    // ... (for: normal)
    // which no longer seems to be an option.
    // Change in Xcode 12.3 from 12.2?
    let title = (sender as AnyObject).title(for:
        UIControl.State(rawValue:
        UIControl.State.RawValue(FP_NORMAL)))

UPDATE 210115: Disregard the above! It turns out that the correct code is

... (for: .normal)

I had forgotten the full stop/period!! But I’m going to leave this here as it demonstrates how a small detail can create a big problem.

Creating icons

Every professional app should have suitable icons. Here are the steps to do this:

1. Create a large icon (say, 1024×1024)—since graphics can be downsized but not upsized without interpolation algorithms, and the result would likely be messy—in .png or .jpg format.¹⁾Remember that .png allows for transparency! I typically use GIMP for this sort of thing.
2. In the Navigation Panel, click on the Assets.xcassets folder; here you can see the various sizes you will need.
3. Use Preview to import the large icon, and > Tools to create smaller sized versions. Of course, if the large icon was created with GIMP, one may as well use the image resizing tool there….²⁾I’ve read some threads which suggest using ImageMagick instead. I’m looking into it; it certainly would be easier to have a batch file which can create all needed icons from a master! As a minimum, one should create the following (XCode will interpolate the others as required):
   1. 180 x 180
   2. 120 x 120
   3. 87 x 87
   4. 80 x 80
   5. 58 x 58
4. Drag the various icons to the appropriate places in the assets folder.

UPDATE 210115: I’m looking at putting together a Script-fu script for GIMP to take an icon and produce all the necessary icon sizes automatically.³⁾I’m working on a tutorial at the moment. But if someone beats me to it, let me know!

Launch screen

Remember to create a launch screen, as this will display while the app is loading. This can make a difference to the user experience if/when the app takes a while to load.

This is quite simple to do:

1. the Navigation Panel, click on LaunchScreen.storyboard.
2. Place a label with text, an image, or whatever you would like the user to see while the app is loading.