hi - thanks for the very fast response :-)
My set up pushes a large JS file into the core, does some work, and then recycles (by just nullifying the JSContext object, as you do). If I look at memory consumption, it goes up when I insert the javascript into the core and execute JavaScript functions (in my case it jumps by about 100MB as I have a lot of JavaScript code ...) On dereferencing the JSContext and looping round, no discernible drop in memory happens. If I then loop back I end up increasing memory by approx 100MB each time ... so the memory consumption grows a lot :-)
I'll see if I can create a more simple setup and share it. My current app is not really something that is easy to work with :-)
chris
knittedman007
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Hi - this was super helpful. Sorry I took so long to get back on this but your suggestions help me identify the retain cycle that prevented the JS Core from being cleaned up properly. I had a thread I was running (handling timers initiated in the JS layer) but when the thread was shut down I did not do it cleanly (I just blindly called Thread.exit()) but I needed to shut the thread properly and let it deallocate any retained references. Once I did that i suddenly saw the retain cycles disappear.
For me this seems limited to the iOS version - and for now just on a simulator (not been able to try on a real device yet... until 17.5 is released officially). I am using Xcode 15.4 Beta to build the App, but it works just fine in ios 17.4 or earlier.
I also tried on VisionOS 1.2 (beta) and this works fine. For completeness I also tried iPad (17.5 beta) but that has the same issue iPhone 17.5 has. So it seems a generic issue with ios on iphone and ipad, but it is not an issue with the latest visionOS release.
Not sure what you mean by 'Beta 3' - do you mean iOS 17.5 Beta 3? Currently my Xcode 15.4 Beta only has ios 17.5 beta 2 so I am not able to verify if beta 3 fixes this untl this is available from Apple.
For completeness, I created the simplest app possible that illustrates this:
//
// ContentView.swift
// TestWKWebView
//
//
import SwiftUI
import WebKit
struct ContentView: View {
var body: some View {
SVGWebView()
}
}
struct SVGWebView: UIViewRepresentable {
let svg: String = "<html><head><meta name=\"viewport\" content=\"width=device-width, initial-scale=1\" /><title>Hello ...</title></head><body><p>Greetings ...</p></body></html>"
func makeUIView(context: Context) -> WKWebView {
return WKWebView(frame: CGRect.zero)
}
func updateUIView(_ webView: WKWebView, context: Context) {
webView.loadHTMLString(svg, baseURL: nil)
}
}
#Preview {
ContentView()
}
This fails too, as I suspected, but worth doing anyway. It works fine on ios 17.5 or earlier.
I just tried latest Xcode 15.4 RC with a new 17.5 Beta release and the problem is resolved :-)
So I assume the final release will also be OK.
Panic over :-)