lastSyncTime is not being used (sometimes)

[airstance]

Describe the bug
There are times when the delta sync code does not use the correct lastSyncTime

To Reproduce
Steps to reproduce the behavior:

1. Start a sync operation with a delta sync query
2. Perform at least one sync from the server so that lastSyncTime is set
3. Force a new sync operation (rerun application, foreground switch, network toggle)
4. There are times when the lastSyncTime isn't fetched from the cache correctly. It will look somewhat random.

Expected behavior
The lastSyncTime should be the same value as the last successful delta/base sync

Environment(please complete the following information):

• AppSync SDK Version: 2.10.3
• Dependency Manager: Cocoapods
• Swift Version : 4.2+

Additional context
There's a bug in AppSyncSubscriptionWithSync.getOperationHash(). The code uses the description of dictionaries which have no order and can randomly return different string values.

Here's a fix that first sorts the dictionary into an array.

    private func getOperationHash() -> String {
        
        var baseString = ""
        
        let variables = baseQuery.variables?.sorted(by: { $0.0 < $1.0 }).description ?? ""
        baseString = type(of: baseQuery).requestString + variables

        if let subscription = subscription {
            let variables = subscription.variables?.sorted(by: { $0.0 < $1.0 }).description ?? ""
            baseString = type(of: subscription).requestString + variables
        }
        
        if let deltaQuery = deltaQuery {
            let variables = deltaQuery.variables?.sorted(by: { $0.0 < $1.0 }).description ?? ""
            baseString = type(of: deltaQuery).requestString + variables
        }
        AppSyncLog.debug("Creating hash for \(baseString)")
        return AWSSignatureSignerUtility.hash(baseString.data(using: .utf8)!)!.base64EncodedString()
    }

This was the issue that was causing me trouble with #219

These bugs are very time consuming to find and fix.

[rohandubal]

Thanks for the detailed information @airstance

I am working to reproduce this on my side.

[royjit]

This fix has been released in the version 2.14.0

[stale]

This issue has been automatically closed because of inactivity. Please open a new issue if are still encountering problems.