如何在 swift 中使用鼠标拖动来旋转 NSImage

Question

I have looked all over the web and I haven't been able to find a solution that explains how you can rotate an NSImage using mouse drag on Xcode. Anyone done it before?

Answer 1

You need to tell use what platform you are writing for. The fact that you mention NSImage rather than UIImage suggests you are talking about MacOS. You should add the appropriate tag to your question.

I mostly work on iOS these days, so my Mac OS skills are rusty.

You also need to decide if you're going to use UIKit/AppKit or SwiftUI. The industry is moving towards SwiftUI, so you might want to use that rather than AppKit (Mac) or UIKit (iOS).

You need to break the problem into parts and solve each part.

First, build an interface that turns a drag gesture into an increasing value. Do you want the user to drag on your image and have the image rotate as if they are spinning it with the mouse? Or do you want to respond to a drag in a straight line like a slider?

Assuming you're building a Mac App, look at NSPanGestureRecognizer . ( UIPanGestureRecognizer is the equivalent on iOS.)

Once you've got a system for collecting an increasing value from a drag gesture, you will want to turn that into a rotation value and apply that to your image. (actually, to your image view .) You'll want to install your image into an NSImageView, and then set the wantsLayer property on your image view to true . (On iOS all views are backed by layers, but you have to ask for a backing layer on Mac OS.)

Then you will apply a rotation to your view's layer's transform. That will cause the image to rotate around its anchor.

Do not ask me for code. This is not a code writing service, it's a site where people ask for help debugging code that they wrote.

Once you have code written, if you're having problems getting it working, post your code (and a link to a project on Github) and we can help you debug it.