Delay Applying Updates in Data Abstract iOS Apps

Even though the code generated by the Data Abstract for Xcode template for iOS apps is mostly asynchronous, you may notice delays in the UI when applying updates to your server. If you check out the asyncRequest:didFinishApplyingChangesForTables:withErrors: method in DataAccess.m, you’ll see that, once an asynchronous request finishes, your data will be saved to the local briefcase file:

- (void)asyncRequest:(DAAsyncRequest *)request didFinishApplyingChangesForTables:(NSArray *)tables withErrors:(NSArray *)errors
{
	[self saveData];
	[self setBusy:NO];
...

This happens on the main thread and, given a large enough set of data, will cause your app to stutter.

Luckily this is pretty straight forward to address. Cocoa makes it easy enough to run code in a background thread, and that’s exactly what Alexander from RemObjects suggests:

-(void)saveDataInBackground {</pre>
    [self performSelectorInBackground:@selector(saveData) withObject:nil];
}

- (void)asyncRequest:(DAAsyncRequest *)request didFinishApplyingChangesForTables:(NSArray *)tables withErrors:(NSArray *)errors
{
    [self saveDataInBackground];
    [self setBusy:NO];
...

I’ve been using a form of the above solution for a while now and can confirm that things are running smoothly, even with a larger set of data. Alexander let me know that this would be addressed in the Xcode templates for a future DA update.

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