问题
I'm using a UIProgressView and want to stick a image subview to the progress % as in the image below:
I want to get the co-ordinate of the progress tint and red subview as in the figure to "stick" with the progress tint, whatever the progress will be..
回答1:
You can start by vertically centering the image view with the progress view using constraints or programmatically like below.
imageView.center.y = progressView.center.y
Then where ever you are updating the progress, after you can calculate the center x coordinate for the image view using the adjusted progress and width of the progress view.
imageView.center.x = progressView.progress * progressView.frame.width
Although you may need to add padding if the progress view's super view is not the same width.
OR
You could consider using a UISlider; it comes with a progress-bar-like track and a thumb slider that you can customise. This way, you can even have user interaction if need be - otherwise user interaction can be disabled and you can set the progress programmatically.
来源：https://stackoverflow.com/questions/41197694/how-to-get-the-exact-point-of-objects-in-swift