I have an iPhone database app that loads a UIPickerView with data from a table. I want to set the selected row to a particular row from the data in another table.
For example: Let's say I have a UIPickerView that is loaded with X number of names of the iPhone users' friends (the number of names is variable; it could be 1 or 1000 and all are entered into the database by the user). The iPhone user has a preference set that their current best friend is TED. I want the UIPickerView to be position to TED when displayed.
Where do I call selectRow?
I tried in viewDidAppear, but it was never called, in titleForRow which caused all kinds of strange behavior. viewDidLoad and viewWillAppear are out of the question, because I don't know what's in the datasource to the picker yet.
Call it after you retrieve the data. I don't know where you load the data so this is just a mockup of what should work. If this doesn't make sense, let me know where you are loading data so I can piece it together in my head :)
-(void)viewDidLoad
{
// load data from sql
// self.someDataArray = DATAFROMSQL
[picker reloadAllComponents];
[picker selectRow:0 inComponent:0 animated:YES];
}
There is a common issue when a (default) UIPickerView item needs to be selected when the UIPickerView is initially shown. The problem is related to the sequence of events. From reading previous posts, it seems that the [pickerView selectRow:n] is normally called in the view controllers ViewDidLoad event. However, the UiPickerView data is only loaded after the ViewDidLoad event, which means any selection code in ViewDidLoad will have no effect. To remedy, place the selection code in ViewDidAppear;
- (void) viewDidAppear:(BOOL)animated {
[m_pickerView selectRow:nSelectedItem inComponent:0 animated:YES]; }
Place this wherever you initialize the UIView that contains your UIPickerView as a subview:
[myPickerView selectRow:rowWithTedsName inComponent:columnWithNames animated:NO];
I have just found that on the 4.3 SDK's the component loading behaviors are different between the iPhone and the iPad. On the iPhone, I was about to invoke selectRow: right after initializing the view before or after adding to the subview hierarchy. On iPad however, the selectRow call yielded no results. I wound up using a performSelector:withObject:afterDelay: call to wait 0.1 seconds before firing selectRow:inComponent:animated:. This had predictable results on the iPhone and iPad.
For Swift it's simply:
self.picker?.selectRow(0, inComponent: 0, animated: true)
If you want the selected row permanently highlighted use this
myPickerView.subviews[0].subviews[0].subviews[2].backgroundColor = myPickerView.tintColor;
Related
I'm using iOS 8 and Objective c.
If I do a change in the values in one view, I can't see the reflection on my other tabviews. But if I re-run the app, I can see the reflection on the other tabs. Sometimes it works, sometimes it doesn't. How can I make sure that when I tap on a tabview, it will be reload according to the database?
I'm not sure what you are trying in your code, but you can try to implement the viewDidAppear method with a reloadData in your tableView:
- (void)viewDidAppear:(BOOL)animated{
[self.tableView reloadData];
}
[tableView reloadData] is the one you are looking for , this UITableView method refreshes the table view by calling its delegate and data source methods again to get fresh data.
I solved it!
Here is my code:
"TheMaster" is the main tabview. Here selectedIndex can be 0,1,2.... according to the placement of the tab. The leftmost tab has the index 0, and after that 1,2, and so on.
UITabBarController *controller = [self.storyboard instantiateViewControllerWithIdentifier:#"TheMaster"];
controller.selectedIndex=0;
[self presentViewController:controller animated:YES completion:nil ];
I'm having a hard time with my SearchDisplayViewController on iOS 7.
I have a searchBar hidden over a UITableViewController, like
self.tableView.tableHeaderView = searchBar;
Problem is that when I tap on the searchBar to type in something, then the view starts greying out, and I quickly tap the screen in a random point to dismiss it, coming back to the tableView, the searchBar disappears. Totally. Only on iOS 7 though.
Debugging it, the frame is always the same: 0,0,320,44. But the bar is invisible!
Also tried to do
self.tableView.contentOffset = CGPointMake(0,self.searchDisplayController.searchBar.frame.size.height);
still disappears when I do it quickly.
On iOS 6 it works just fine. Problem is only with iOS 7 as far as I'm seeing.
I don't know what it depends on, has anyone encountered the same problem I have?
As of Double tap UISearchBar with search delegate on iOS 7 causes UISearchBar to disappear, I found the workaround to actually work and solved the bug - for now.
- (void)searchDisplayControllerDidEndSearch:(UISearchDisplayController *)controller
{
if (floor(NSFoundationVersionNumber) > NSFoundationVersionNumber_iOS_6_1) {
[self.tableView insertSubview:self.searchDisplayController.searchBar aboveSubview:self.tableView];
}
}
I encountered the same issue, and noticed that searchDisplayControllerDidEndSearch was being called twice. The first time, the superview of self.searchDisplayController.searchBar is the UITableView, and the second time it's still a UIView.
With the accepted answer, I worry about unintended consequences or unneeded overhead from re-inserting the subview every time the search bar is double-tapped, and I also worry about it breaking with future iOS versions. Fortunately, we can take advantage of the superview strangeness like this:
- (void)searchDisplayControllerDidEndSearch:(UISearchDisplayController *)controller {
if (self.tableView != self.searchDisplayController.searchBar.superview) {
[self.tableView insertSubview:self.searchDisplayController.searchBar aboveSubview:self.tableView];
}
}
If I had to guess what was happening, the UISearchBar is automatically creating a temporary UIView as its superview when it's active – this is the view seen when the search is being performed. While the UISearchBar is being dismissed, the superview gets set back to be the UITableView it had before, unless it gets dismissed so quickly that it was never properly initialized, in which case it cleans up improperly and the UITableView never gets the UISearchBar back as its child.
This solution still isn't ideal, and I think Apple must be doing something different in its own apps because their search bar UX feels a bit better. I think it would be better not to handle the second tap in the first place until the UISearchBar was ready. I tried using the other UISearchBarDelegate methods to do this, but I couldn't find an appropriate hook to override the current behavior.
I had the same problem with iOS 7 and I solved it from the apple documentation. The error most people do is that they associate the UISearchBar variable to the self.searchDisplayController.searchBar as the same...! NO NO..! They are 2 different things!!! UISearchBar should be declared and initialized and then wrapped into self.searchDisplayController as searchBar then later wrapped into self.tableView.tableHeaderView by so doing it will not disappear!!!
self.searchBar = [[UISearchBar alloc]initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, 44)];
self.searchDisplayController = [[UISearchDisplayController alloc] initWithSearchBar:self.searchBar contentsController:self];
self.searchDisplayController.delegate = self;
self.searchDisplayController.searchResultsDataSource = self;
self.searchDisplayController.searchResultsDelegate = self;
[self.searchBar setPlaceholder:#"search the hell in me"];
self.tableView.tableHeaderView = self.searchDisplayController.searchBar;
More refined approach for #lehrblogger solution:
- (void)addSearchDisplayControllerBackToTableView {
if ([self.searchDisplayController.searchBar isDescendantOfView:self.tableView] == NO) {
NSLog(#"Search bar is not in current table view, will add it back");
[self.tableView insertSubview:self.searchDisplayController.searchBar aboveSubview:self.tableView];
[self.searchDisplayController setActive:NO animated:YES];
}
}
Reason for this approach: While searching the search bar is moved to search container and the superview of search bar is always some other view other than current table view.
Note: This will dismiss the search, because user tapped more than once on search bar.
In a project I'm writing I get this error when I present a new view controller:
Attempt to present.... while a presentation is in progress!
I think it happens because I first present a new view controller, and then in that view I present another view controller.
- (void)loadLabelSettings {
LabelSettingsViewController *labelSettings =
[[LabelSettingsViewController alloc] init];
labelSettings.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentViewController:labelSettings animated:YES completion:nil];
}
The program doesn't crash or anything it runs just fine, and there is no errors or warnings in my code. So my question is: Is it something I should be concerned with and if yes how do I solve it?
Thanks in advance :)
It is, like you said, probably caused by presenting two view controllers at the same time. Wait with presenting the second view controller until the first one has been fully presented. A good location would be to do this in viewDidAppear.
In my case, I connected a UIViewControllers UIButton with a second UIViewController by a UIStoryboardSegue. Inside my code a called it a second time programmatically. So pressing the UIButton caused presenting the specified view two times.
I figured out my problem, as Scott wrote it was because I was presenting 2 view controllers at the same time. It happened because I had a button that had a UILongPressGestureRecognizer, that showed the new view controller. The problem was that when using a UILongPressGestureRecognizer, the method that is being called, is called twice. First when the long press is detected and when your finger is released from the screen. So the presentViewController method of the same view, was called twice. I fixed this by only reacting to the first detection. Here is the code :
- (void)loadButtonSettings:(UILongPressGestureRecognizer *)recognizer {
if (recognizer.state == UIGestureRecognizerStateBegan) {
}
}
I have set up a demo application with a simple UITableViewController with no contents, but an 'Add' button in the toolbar. This launches a modal view controller which is again empty other than a 'cancel' button. The cancel button just tells its delegate (the UITableViewController) to dismiss the modal.
I then added an NSLog statement in the UITableViewController's numberOfSectionsInTableView method.
Ordinarily, when the table view controller loads I see two calls to numberOfSectionsInTableView. When I open and dismiss the modal (which returns to the UITableViewController) I see no further calls to numberOfSectionsInTableView.
However, if I return 0 from numberOfSectionsInTableView, in addition to the two calls on display, I also see an additional numberOfSections call when the modal is dismissed.
This only happens when numberOfSectionsInTableView returns 0, and I have added no additional code to my project besides that mentioned. This is easily verifiable by setting up a couple of controllers as I've described and modifying the result from numberOfSectionsInTableView.
My questions:
Why is the UITableView calling numberOfSectionsInTableView on return from a modal view?
Why is it only doing this if numberOfSectionsInTableView returns 0?
In addition to numberOfSectionsInTableView, the UITableViewController is also calling cellForRowAtIndex: when the modal is dismissed. In fact, it is attempting to display the new contents of its dataSource. How am I meant to manually animate a row insertion if the first row added is going to already be updated automatically? Shouldn't it be left to me to make sure that my UITableView is consistent with its dataSource?
What property is the UITableViewController checking to know that there is one or more sections (and therefore ask my delegate how many sections)? It can't be numberOfSectionsInTableView itself, since I would see it called whenever I return from the modal, not only when numberOfSections = 0.
From UITableViewController docs:
When the table view is about to appear the first time it’s loaded, the
table-view controller reloads the table view’s data... The
UITableViewController class implements this in the superclass method
viewWillAppear:
If you watch in the debugger, the second call upon app launch is from UITableViewController's viewWillAppear: implementation - specifically the part referred to above, where tableView is sent the reloadData message.
Now, the first call to numberOfSectionsInTableView: on launch is also from UITableViewController's implementation of viewWillAppear: but not directly from that implementation's call to -[UITableView reloadData]. I'm not sure what the first call is all about.
But, to your question, the call to numberOfSectionsInTableView: that happens when dismissing the modal has exactly the same call stack as the second call from applicationDidFinishLaunching:withOptions:. My hypothesis then is that UITableView interprets having zero sections as being in a state where it has not loaded at all. That does make some sense actually. I'd consider an "empty" table view to be one without any rows, but one without any sections seems almost "uninitialized" to me. Furthermore the UITableViewDataSource documentation implies UITableView has by default one section. Returning zero from this method would be inconsistent with that assumption of the docs as well.
Now, to your concern about animation - if you give the table an empty section to work with, you will be able to have full control over inserting the first row with whatever animation you'd like, and not be locked in to when you need to reload.
I think the moral of the story is, don't return zero sections unless you really, really need to for some reason. The title of your post refers to this table view being "empty" as well but I think it's clear the framework finds zero sections to not be empty but unloaded.
Hope this helps! And thanks for posting the sample project for me to play around with.
Perhaps the delegate just couldn't believe its eyes. But seriously, since a table view has to have at least one section, passing 0 doesn't make any sense. Why do it? You pass it an invalid argument and it gives you back a weird response. As to why it doesn't ask for number of sections when you pass 1, I think it's because it doesn't need to know at that point (coming back from the modal view controller) -- the table view has already been populated (if there were some data) and you haven't changed anything in the model, so it doesn't need to update.
I added a few lines to your example project to slide in a row each time you return from the modal view controller, which is what I think you're trying to do. I added an int property num for the return value of numberOfRowsInSection, added an array to populate the table, and a call to insertRowsAtIndexPaths from the modal view controller dismissal method.
- (void)viewDidLoad
{
_num = 0;
self.theData = #[#"one",#"two",#"three"];
[super viewDidLoad];
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd
target:self
action:#selector(addRecipe)];
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
NSLog(#"# sections requested");
//when 0, this fires on return from the modal. When 1, it does not.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
NSLog(#"in numberOfRows in section");
return _num;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"in cellForRowAtIndexPath");
UITableViewCell *cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:nil];
cell.textLabel.text = [self.theData objectAtIndex:indexPath.row];
return cell;
}
- (void)addRecipe
{
//create the modal and suscribe for delegate notifications
AddRecipeViewController *addRecipeController = [[AddRecipeViewController alloc]initWithStyle:UITableViewStyleGrouped];
addRecipeController.delegate = self;
//display the modal in a navigation controller
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:addRecipeController];
[self.navigationController presentModalViewController:navController animated:YES];
}
- (void)addRecipeVC:(AddRecipeViewController *)addRecipeVC didAddRecipe:(NSString *)recipe
{
[self dismissModalViewControllerAnimated:YES];
_num += 1;
[self performSelector:#selector(addRow) withObject:nil afterDelay:.5];
}
-(void)addRow {
[self.tableView insertRowsAtIndexPaths:#[[NSIndexPath indexPathForRow:_num-1 inSection:0]] withRowAnimation:UITableViewRowAnimationRight];
}
The tableview checks number of sections when it's populating the table view with data!
Since the table can be divided into sections, it has to know specifically how many sections to divide it into.
When you reload the data, the number of sections is also checked.
Because every time the table view has to take action in accessing either the data of the table, like what row you tapped, and in what section, or populating the data table, the number of sections has to be known!
Hope this helped!
Similar to this question: Adding subview, gets delayed?
But I don't think you can pushViewController in a separate thread so is this really impossible?
Here is what I'm trying to do:
I have a TableView and when a cell is pressed, I want to call
[self.view addSubview:LoadingView]
to display an overlay with a spinner. Then I call
self.navigationController.navigationBar.hidden = NO;
[self.navigationController pushViewController:newGameViewController animated:YES];
However, the subview only displays for a split second (~1-4 seconds after the cell selection occurs while it waits for the new viewcontroller to initialize).
Is there any way to get some sort of loading indicator to occur at the instant the cell is selected?
Okay. What about this. In your didSelectRowAtIndexPath start your spinner (via addSubview ...) and start loading your stuff from the server. If that's finished remove the spinner an push your new view controller onto the stack. Make sure the user can't touch any other cell during that time. By the way. From a users perspective I'd find it mor intuitive if the new controller is loaded immediately and displays some waiting message.
Or the other way around: The newGameViewController displays the spinner and starts loading the data from the server in a background thread. When the data is complete, remove the spinner and display the data. That way the user could even go back if she doesn't want to wait.
You do not need to add code before pushing newGameViewController.
Inside viewDidLoad of newGameViewController, write the code of displaying spinner. To get the updated UI, just insert a delay before calling a web API.
inside GameViewController.m
-(void) viewDidLoad
{
[self.view addSubview:LoadingView];
[self performSelector:#selector(callWebAPI) afterDelay:0.1];
}
-(void) callWebAPI
{
//Handle network activity here..
}