I want to create a iOS application with a tableview which show a list string data from API. The data can be update continuously so I want my tableview can update datasource continuously.
This app like exchange rate board in a bank.
Anyone give me a some suggestion? Thank you very much!
If you do not need animation, you can call -(void)reloadDate anytime when your data is updated.
<...>
[self updateDataSource];
[self.tableView reloadData];
<...>
If you need some animation you should use other methods:
<....>
[self.tableView beginUpdate];
[self updateDataSource];
[self.tableView insertRowsAtIndexPaths:<inserted rows index paths> withRowAnimation:<animation>];
[self.tableView endUpdates];
<...>
Related
UITableView not reloading data. I am using pull to load more library to load data on scroll
I have tried
dispatch_sync(dispatch_get_main_queue(), ^{
[self.pullTableView reloadData];
});
and
[self.pullTableView performSelectorOnMainThread:#selector(reloadData)
withObject:nil
waitUntilDone:YES];
Thanks in advance.
reloadData won't actually fetch data of the internet or your datasource from you, it will just call back the function of numberOfSection numberOfRowInSection: and cellForRowAtIndexPath:
Before calling reload data, you should call the method that go and fetch the new content, then call reloadData
Put your entire class view controller code if you want more help.
I have an app with a UITableView which can delete cells using a row action. However, if I do two in quick succession, the app crashes with a BAD_EXEC.
The problem is clearly timing related. I'm asking the table to do something else before it's quite finished with the old. It could be the animations or it could be the removal of cells.
Either way, calling reloadData on the tableview before I start seems to fix it. There are two problems with this solution.
Firstly, reloadData interferes with some of the niceness of the usual row removal animations. It's no biggie but I'd prefer it with all animations intact.
Secondly, I still don't fully understand what's happening.
Can any one help me understand and/or suggest a better solution?
Here's the code...
-(void) rowActionPressedInIndexPath: (NSIndexPath *)indexPath timing:(Timing) doTaskWhen
{
[self.tableView reloadData]; // This is my current solution
[self.tableView beginUpdates];
ToDoTask *toDo = [self removeTaskFromTableViewAtIndexPath:indexPath];
toDo.timing = doTaskWhen; // Just some data model updating. Has no effect on anything else here.
[self.tableView endUpdates];
}
removeTaskFromTableView is mostly code to work out if I need to delete an entire section or a row. I've confirmed the app makes the right choice and the bug works either way so the only relevant line from the method is...
[self.tableView deleteRowsAtIndexPaths:#[indexPath] withRowAnimation:UITableViewRowAnimationLeft];
Edit: I have noticed that the standard delete row action provided by the system does not allow me to move that fast. There is an in-built delay which (presumably) prevents this exact problem.
-(void) rowActionPressedInIndexPath: (NSIndexPath *)indexPath timing:(Timing) doTaskWhen
{
// [self.tableView reloadData]; // This is my current solution
[self.tableView beginUpdates];
ToDoTask *toDo = [self removeTaskFromTableViewAtIndexPath:indexPath];
toDo.timing = doTaskWhen; // Just some data model updating. Has no effect on anything else here.
[self.tableView endUpdates];
}
Or try to reload table view in main thread.
I'm an amateur at best, and stuck on this error! surely something simple...
- (void)addTapped:(id)sender {
TechToolboxDoc *newDoc = [[TechToolboxDoc alloc] initWithTitle:#"New Item" thumbImage:nil fullImage:nil];
[_itemArray addObject:newDoc];
//[self.tableView beginUpdates];
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:_itemArray.count-1 inSection:0];
NSArray *indexPaths = [NSArray arrayWithObject:indexPath];
NSLog(#"%#",indexPath);
[self.tableView insertRowsAtIndexPaths:indexPaths withRowAnimation:YES];
[self.tableView selectRowAtIndexPath:indexPath animated:YES scrollPosition:UITableViewScrollPositionMiddle];
[self performSegueWithIdentifier:#"MySegue" sender:self];
//[self.tableView endUpdates];
it is breaking on the line the says
[self.tableView insertRowsAtIndexPaths:indexPaths withRowAnimation:YES];
You need to add [UITableView beginUpdates] and [UITableView endUpdates] around:
[self.tableView insertRowsAtIndexPaths:indexPaths withRowAnimation:YES];
From the class reference:
Note the behavior of this method when it is called in an animation
block defined by the beginUpdates and endUpdates methods. UITableView
defers any insertions of rows or sections until after it has handled
the deletions of rows or sections. This happens regardless of ordering
of the insertion and deletion method calls. This is unlike inserting
or removing an item in a mutable array, where the operation can affect
the array index used for the successive insertion or removal
operation. For more on this subject, see Batch Insertion, Deletion,
and Reloading of Rows and Sections in Table View Programming Guide for
iOS.
I think you are inserting the row in your tableView but not updating the number of rows at section that's why you are getting error in this line. So along with inserting the row You should also increase the array count or whatever you are using to show the number of rows in table view.
In my case, I was using Parse and I deleted a few users (one of which was my iPhone simulator). I got this error whenever refreshing the tableView.
I just deleted the app from the Simulator and made a new account and it works flawlessly.
#droppy's answer helped give me the lightbulb moment of what was wrong!
Hope that helps someone.
I have spent hours searching for the solution with out any luck. I am trying to delete a row (also deselect same row) programmatically. After row deletion call below, UITableViewDelgate methods get called expectedly and data source is updated but UITableView is not refreshed. deselectRowAtIndexPath call also does not work. I tried all kinds of scenarios as shown by commented lines.
Here is my code:
checkoutPerson is called as a result of observer listening for NSNotificationCenter messages.
- (void) checkoutPerson: (NSNumber*) personId {
Person *person = [_people objectForKey:personId];
if( person )
{
// Remove person from data source
int rowIndex = person.rowIndex;
S2Log(#"Deleting row number=%d", rowIndex);
[_allKeys removeObjectAtIndex:rowIndex];
[_people removeObjectForKey: personId];
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:rowIndex inSection:0];
//[[self tableView] beginUpdates];
[self.tableView deselectRowAtIndexPath:indexPath animated:YES];
S2Log(#"Deleting indexPath row=%d", [indexPath row]);
[self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
withRowAnimation:UITableViewRowAnimationFade];
//[[self tableView] endUpdates];
S2Log(#"Reloading data");
//[[self tableView] reloadData];
//[self performSelector:#selector(refreshView) withObject:nil afterDelay:1.5];
//[self.tableView performSelectorOnMainThread:#selector(reloadData) withObject:nil waitUntilDone:YES];
}
}
I will appreciate for help.
Thanks
-Virendra
I believe deleted cell is not being recycled. If I delete row in the middle, last row is always erased (since there is one less item) but the deleted row remains.
Use the above code between two function for table view
[tableView beginUpdates];
// the deletion code from data source and UITableView
[tableView endUpdates];
By calling this functions you are telling UITableView that you are about to make updates for deleting your cell.
Edit
The other problem I see with your code is you first delete the data from the data source.
Now you are asking for the UITableViewCell (which actually reloads the UITableView)
and then you are deleting the row from UITableView
I guess you should fetch the UITableViewCell before deleting values from your data source.
I found the problem. It has nothing to do with the code I posted above. It is syncing problem between visual display and the contents of data source. I have an embedded UITableView as part of a composite view. In composite view's controller, I was wiring up UITableView's delegate and data source to an instance of UITableViewController. Instead of this, I should have set UITableViewController's tableView property to the embedded UITableView. It seems that UITableView has to be contained within UITableViewController in order to correctly sync up table view visual display to the contents of data source. This also fixes row deselection and scrolling. I also needed to delay reloadData call in which case deleteRowsAtIndexPaths:withRowAnimation is not required. All you need is to modify the contents of your data source and call reloadData with a delay of 1.5 Seconds.
Thanks to all for great help.
I have a table view with a detail label on the right. This label is populated by a entity that I populate from a JSON call in my connectionDidFinishLoading function. The problem is that the cellFromRowAtIndexPath function fires before the connectionDidFinishLoading function so I don't see the values in my table view until I pull down on the screen which redraws the page. I have tried refreshing the table view at the end of both of these functions but that doesn't see to work. Can someone give me a clue as to why this is happening and how I can fix it please.
you have to reload your table data at the end of your connectionDidFinishLoading.
two ways:
The first:
[tableView reloadData];
The second:
NSArray* rows = [tableView indexPathsForVisibleRows];
[tableView beginUpdates];
[tableView reloadRowsAtIndexPaths:rows withRowAnimation:UITableViewRowAnimationFade];
[tableView endUpdates];
Are you calling reloadData in the main thread? connectionDidFinishLoading sounds like it's running in a background thread.
After populating, call reloadData on the tableView.
This should do it. All UI updates and manipulations must be performed from the main thread
dispatch_async(dispatch_get_main_queue(), ^{
[self.tableView reloadData];
});