
# Common Core Data Issues

While using Core Data with [[swift]] and [[swiftui]] I've ran into a few _gotchas_. This page documents those and how I fixed them.

### Merge Conflicts

`Could not merge changes ... with oldVersion = 5 and newVersion = 6`

refresh object before updating and saving new changes

```swift
let myObject = viewContext.objectWithID(managedObjectId)
viewContext.refresh(myObject, mergeChanges: true)
myObject.property = newValue
```

https://stackoverflow.com/questions/39508077/coredata-merge-conflict-shows-managed-object-version-change-not-data

### Observed Object

When passing an Core Data object into a child view, make sure the variable is marked as observable, otherwise it won't receive updates if modified.

```swift
struct ChildView: View {
	@ObservedObject var myModel: MyModel
	
 	var body: some View {
   		// ...
  	}
}
```

### Disable Core Data and CloudKit Debug Logs

```shell
-com.apple.CoreData.Logging.stderr 0
-com.apple.CoreData.CloudKitDebug 0
```

https://stackoverflow.com/a/59125651/1345618


core-data-common-issues


# Programming Languages

Programming languages.

There are a lot of them. Some are good, others are bad.

Experimenting with language design is something I toy with on the side.

- [[typescript]]
- [[swift]]
- [[haskell]]
- [[Rust]]

## My Languages

- [[krill]]
- [[stck]]
- [[vraw]]


languages


# Property Wrappers

Pretty awesome language feature in [[swift]]

```swift
@PropertyWrapper
var myVariable = 10
```

property-wrappers


# SwiftUI

Reactive framework for creating user interfaces for [[ios]] and macOS in [[swift]].