Can't fetch small images, API MISUSE, SwiftUI

[zzzkk]

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Issue Description

What

Some images fetch always fails, my observation is that it applies only to smaller images like
https://www.google.com/images/branding/googlelogo/1x/googlelogo_color_272x92dp.png
for this https://raw.githubusercontent.com/onevcat/Kingfisher/master/images/logo.png it works fine 🤔

Reproduce

KFImage.url(url)
    .onSuccess { r in
        print(r) // never called
    }
    .placeholder { p in
        ProgressView(p) // shows up to 100%
    }

Other Comment

console output:

API MISUSE: NSURLSession delegate KFSessionDelegate: <KFSessionDelegate: 0x28252ac40> (0x28252ac40)
API MISUSE: dataTask:willCacheResponse:completionHandler: completion handler not called

• completion for sessionTask.onTaskDone.delegate(on: self) { (self, done) in is never called
• using debuging tool I can see successful http response with image

[onevcat]

Ummm. It is weird. Kingfisher never implements the willCacheResponse delegate method. I will see if I can reproduce it and try to understand what is going on.

[onevcat]

Not sure I am doing the right thing or not, but when running in the demo project, it seems everything goes well:

@zzzkk Is it a 100% reproducible issue? Can you also try on some other simulator/device/network condition and share more information about it? (Or are you trying to extend KFSessionDelegate (or SessionDelegate in Swift) and implement some willCacheResponse method in your project?)

[onevcat]

Maybe a reproducible sample repo would be a great help for us to track this issue better!

[zzzkk]

right, issue reproduces only in my repo, no matter which device/network/etc
I'm not extending session delegate or modifing other networking related logic

but

maybe some other external library I use is messing it up?
I'll try to turn them off one by one and check if it fixes Kingfisher behaviour 🤔

[onevcat]

maybe some other external library I use is messing it up?

Maybe. But actually, that's beyond what I can imagine... Kingfisher is creating its own URLSession when downloading an image and the session delegate is also defined inside the project. So not sure what can cause the "API MISUSE". Please let me know if you can find anything. Thanks!

[zzzkk]

all right, I found it!
it is the debugging tool I use, it seems they have some faulty swizzling 😞
dbukowski/DBDebugToolkit#68

thanks for quick response and help @onevcat

[onevcat]

Thanks for the feedback. Great to hear you found that!

That is a very common mistake that one forgets calling the handler. I guess once DBDebugToolKit fixes it, everything should go back working.