onSuccess is not executed if already cached

[foolbear]

I want get the uiimage of remote and save it to the photo library, onSuccess is a good solution, but I found that onSuccess is not executed if already cached, I cannot get the uiimage from here every time. Is this a issue or is there another solution for this?

WebImage(url: URL(string: "https://nokiatech.github.io/heif/content/images/ski_jump_1440x960.heic"))
        .onSuccess { image, cacheType in
            // Success
            print("\(image), \(cacheType)")
        }

and cacheType = SDImageCacheType?
20-02-01 16:11:19 CardView[37], ContentView: <UIImage:0x2830f3060 anonymous {1310, 256}>, SDImageCacheType

[dreampiggy]

Seems because when hitting image cache, which is Sync. So by the time you access .onSuccess, the internel manager's completionBlock already been called. 😓

I'll provide a quick fix, to make async dispatch for manager. Maybe another 1.0.0-beta2 version ? Or do I need to releasse a backward patch on 0.10.x ? @foolbear

[dreampiggy]

Seems we should not make it async, because SwiftUI may like to create another new Struct when display changes, such as entering the Edit Mode of list.

I'll find the solution soon.

And actually, if you just need the image, don't need any view UI, you can directly call SDWebImageManager.loadImage, no View is needed...

[foolbear]

@dreampiggy thanks very much. I using SDWebImageSwiftUI by Swift Package, so I must wait for your next tag.

[dreampiggy]

@foolbear Does this test case cover you use case ? here: https://github.com/SDWebImage/SDWebImageSwiftUI/pull/77/files#diff-0e818d73246b1f459bc6acc13da17823R109

I test this fix the issue.

Also, the change is compatible with List Entering Edit Mode. (This is a edge case that SwiftUI create your View struct without calling onAppear...)

[dreampiggy]

I using SDWebImageSwiftUI by Swift Package, so I must wait for your next tag.

This is not related to the package manager... For SwiftPM, you can choose to use:

• Git Tag
• Git Branch
• Git Commit
• Local Path

4 types of dependency.

You can just clone this repo, checkout that PR's branch (bugfix_onSuccess_when_memory_cache_hit), then drag the entire repo folder into your Xcode Project, Xcode will override the remote dependency with the local one, you can test and debug.

After you can ensure this patch work, please have a reply, so I can release a new version.

See: https://developer.apple.com/documentation/swift_packages/editing_a_package_dependency_as_a_local_package?language=objc

[dreampiggy]

@foolbear If you previouslly use 0.x version (0.10.2 or somthing), I've already released one patch version v0.10.3 for this. New 1.0.0-beta2 version will comming soon.

Note on the middle or end of February, I'll release official 1.0.0 version, which break some of APIs from 0.x and provide a better support for WebImage on animation...

So, currently small patches will pick back to 0.x version, but after 1.0.0 released, no more changes will be applied on 0.x version.

[foolbear]

@dreampiggy
YES, I can use SDWebImageManager.shared.loadImage() to do my job.

in v0.10.3, onSuccess executed every time. but I cannot get the UIImage, why?
this is my sample code:

import SDWebImageSwiftUI

struct TestImageView: View {
    @State private var uiImageFromRemote: UIImage? = nil
    
    var body: some View {
        VStack {
            WebImage(url: URL(string: "https://avatars0.githubusercontent.com/u/827316?s=88&v=4"))
                .onSuccess { image, cacheType in
                    DispatchQueue.main.async {
                        self.uiImageFromRemote = image
                    }
            }
            .resizable()
            .indicator(.activity)
            .transition(.fade)
            .scaledToFit()
            uiImageFromRemote.map { uiimage in
                Button(action: { /*save uiImageFromRemote to photo library*/ }) {
                    Image(uiImage: uiimage).frame(width: 100, height: 100)
                }
            }
        }
    }
}

[dreampiggy]

@foolbear The sample code works well. Do you have something extra config (like WebP?) I can not reproduce your problem after that PR #77 was merged.

[dreampiggy]

If you means "I want to update another View based on the onSuccess callback". Sadly, you business SwiftUI code is wrong.

Anything trigger the update value using @State, SwiftUI will call your body again. So maybe this onSuccess will callback twice because SwiftUI create two WebImage struct and View Tree (It's OK here maybe)

And also, common mistake there embed a Image inside Button, check our readme again: Using Image/WebImage/AnimatedImage in Button/NavigationLink

Fix your code again and run:

Actually, we as a framework, does not mean we teach any SwiftUI toturial or tips. 😅 Something about SwiftUI itself, it's better to learn it from online resources. Like:

• Hacking With Swift - SwiftUI
• 100 Days SwiftUI

[foolbear]

@dreampiggy roger that and thanks!