I'm building an iPhone application, where I have a table view with items that can be checked on or off. When the user has checked the selected items, I have to send that information back to my server. However, I don't know the optimal way to do this. Should I load the information into an array? Maybe a dictionary? And can you give specific examples of how to do this with code?
Thanks.
No one?
Update
To be clear, everything regarding URL connections is taken care of. All I need is a way to sort the information in an array or the like, where the index path of the items is used to represent the checked table view cells. After that, I'll convert the information to JSON, which I will then parse on the server. I have a JSON encode/decode library, so I don't need any information on how to do that.
OK, this seems to solve my problem. If someone knows a more elegant solution, please let me know.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
if ([self.tableView cellForRowAtIndexPath:indexPath].accessoryType == UITableViewCellAccessoryCheckmark) {
[self.tableView cellForRowAtIndexPath:indexPath].accessoryType = UITableViewCellAccessoryNone;
[self.tableView cellForRowAtIndexPath:indexPath].textLabel.textColor = [UIColor colorWithRed:0.0 / 255 green:0.0 / 255 blue:0.0 / 255 alpha:1];
[selectedSources removeObject:[NSNumber numberWithInt:indexPath.row]];
} else {
[self.tableView cellForRowAtIndexPath:indexPath].accessoryType = UITableViewCellAccessoryCheckmark;
[self.tableView cellForRowAtIndexPath:indexPath].textLabel.textColor = [UIColor colorWithRed:72.0 / 255 green:104.0 / 255 blue:152.0 / 255 alpha:1];
[selectedSources addObject:[NSNumber numberWithInt:indexPath.row]];
}
[self.tableView deselectRowAtIndexPath:indexPath animated:YES];
}
selectedSources is an NSMutableArray, which I then JSON encode and send to my server. Based on the index path, I can then identify which table view cells have been checked/unchecked server side.
Thanks, Anna!
Related
I'm trying to figure out how to populate a table from a JSON array. So far, I can populate my table cells perfectly fine by using the following code:
self.countries = [[NSArray alloc]initWithObjects:#"Argentina",#"China",#"Russia",nil];
Concerning the JSON, I can successfully retrieve one line of text at a time and display it in a label. My goal is to populate an entire table view from a JSON array. I tried using the following code, but it still won't populate my table. Obviously I'm doing something wrong, but I searched everywhere and still can't figure it out:
NSURL *url = [NSURL URLWithString:#"http://BlahBlahBlah.com/CountryList"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON)
{
NSLog(#"%#",[JSON objectForKey:#"COUNTRIES"]);
self.countries = [JSON objectForKey:#"COUNTRIES"];
}
failure:nil];
[operation start];
I am positive that the data is being retrieved, because the NSLog outputs the text perfectly fine. But when I try setting my array equal to the JSON array, nothing happens. I know the code is probably wrong, but I think I'm on the right track. Your help would be much appreciated.
EDIT:
This is the text in the JSON file I'm using:
{
"COUNTRIES": ["Argentina", "China", "Russia",]
}
-Miles
It seems that you need some basic JSON parsing. If you only target iOS 5.0 and above devices, then you should use NSJSONSerialization. If you need to support earlier iOS versions, then I really recommend the open source JSONKit framework.
Having recommended the above, I myself almost always use the Sensible TableView framework to fetch all data from my web service and automatically display it on a table view. Saves me a ton of manual labor and makes app maintenance a breeze, so it's probably something to consider too. Good luck!
I am trying to create a UIActivityViewController that lets the user send in feedback about the current web page that is being viewed. I want to have a separate button from the Mail icon to pop up with a compose window with a recipient set, subject set, and the message body to include some text and the current URL (I get the URL with: NSURL *urlStringToShare = _webView.request.URL; in the RootViewController). Any ideas how to do this? Thanks for your help.
For example, I already have an IBAction that does this:
- (IBAction)showEmail:(id)sender {
// Email Subject
NSString *emailTitle = #"Feedback on your latest column from the GlennKessler App:";
// Email Content
NSString *messageBody3 = #"I disagree with your latest Fact Check and the number of pinocchios you gave. This is what I would rate it instead and why:";
// To address
NSArray *toRecipents = [NSArray arrayWithObject:#"blah#la.com"];
MFMailComposeViewController *mc = [[MFMailComposeViewController alloc] init];
mc.mailComposeDelegate = self;
[mc setSubject:emailTitle];
[mc setMessageBody:messageBody3 isHTML:NO];
[mc setToRecipients:toRecipents];
// Present mail view controller on screen
[self presentViewController:mc animated:YES completion:NULL];
}
Any way to convert this into a UIActivityViewController item with an icon? Thanks!
Try using this, You can create a number of Custom Activityies such as mail using the Library found at this link:
https://github.com/imulus/OWActivityViewController
I have some data that is fetched in another thread that updates a UICollectionView's header. However, I've not found an efficient way of reloading a supplementary view such as a header or footer.
I can call collectionView reloadSections:, but this reloads the entire section which is unnecessary. collectionView reloadItemsAtIndexPaths: only seems to target cells (not supplementary views). And calling setNeedsDisplay on the header itself doesn't appear to work either. Am I missing something?
You can also use (the lazy way)
collectionView.collectionViewLayout.invalidateLayout() // swift
[[_collectionView collectionViewLayout] invalidateLayout] // objc
More complex would be to provide a context
collectionView.collectionViewLayout.invalidateLayout(with: context) // swift
[[_collectionView collectionViewLayout] invalidateLayoutWithContext:context] // objc
You can then make a or configure the context yourself to inform about what should be updated see: UICollectionViewLayoutInvalidationContext
It has a function in there that you can override:
invalidateSupplementaryElements(ofKind:at:) // swift
Another option is (if you have already loaded the correct header/footer/supplementary view) and you only want to update the view with the new data than you can use one of the following functions to retrieve it:
supplementaryView(forElementKind:at:) // get specific one
visibleSupplementaryViews(ofKind:) // all visible ones
Same goes for visible cells with visibleCells. The advantage of just getting the view and not reloading a view entirely is that the cells retains it state. This is espically nice with table view cells when they use swipe to delete/edit/etc since that state is lost after reloading the cell.
If you feel fanatic you can of course also write some extensions to retrieve only cells/supplementary views of a given kind using generics
if let view = supplementaryView(forType: MySupplementaryView.self, at: indexPath) {
configure(view, at indexPath)
}
this assumes that you have a function that registers/dequeues views in example with their class name. I made a post about this here
I just ran into the same problem, and I ended up looking up the view using its tag to edit a label:
UICollectionReusableView *footer = (UICollectionReusableView*)[self.collectionView viewWithTag:999];
UILabel *footerLabel = (UILabel*)[footer viewWithTag:100];
Like you said it is unnecessary to reload an entire section, which cancels out any animation on cells as well. My solution isn't ideal, but it's easy enough.
Swift 3/4/5 version:
collectionView.collectionViewLayout.invalidateLayout()
Caution!
If you change the number of collectionView items at the same time (for example you show the footer only if all cells were loaded), it will crash. You need to reload the data first, to make sure that the number of items is the same before and after invalidateLayout():
collectionView.reloadData()
collectionView.collectionViewLayout.invalidateLayout()
I got the same problem. I tried #BobVorks's answer and it is working fine, if only the cell was reused else it won't. So, I tried finding a more cleaner way to achieve this and I came up reloading the whole UICollectionView after the performBatchUpdate (completion block) and it is working great. It reloads the Collection Without any cancellation of animation in the insertItemsAtIndexPath. Actually I personally up voted recent 2 answers cause i find it working but in my case, this is the cleanest way to do it.
[self.collectionView performBatchUpdates:^{
// perform indexpaths insertion
} completion:^(BOOL finished) {
[self.collectionView reloadData];
}];
[UIView performWithoutAnimation:^{
[self.collectionView reloadSections:[NSIndexSet indexSetWithIndex:4]];
}];
[UIView performWithoutAnimation:^{
[self.collectionView reloadData];
}];
Here are two ways you could do it.
1.
Create a mutable model to back the data that will eventually be available. Use KVO in inherited class of UICollectionReusableView to observe the changes and update the header view with the new data as it comes available.
[model addObserver:headerView
forKeyPath:#"path_To_Header_Data_I_care_about"
options:(NSKeyValueObservingOptionNew |
NSKeyValueObservingOptionOld)
context:NULL];
then implement listener method in header view
- (void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context
2.
add notification listener to the view and post a notification when the data has successfully come available. Downside is that this is application wide and not a clean design.
// place in shared header file
#define HEADER_DATA_AVAILABLE #"Header Data Available Notification Name"
// object can contain userData property which could hole data needed.
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(headerDataAvailable:) name:HEADER_DATA_AVAILABLE object:nil];
[[NSNotificationCenter defaultCenter] postNotificationName:HEADER_DATA_AVAILABLE object:nil];
let headerView = collectionView.visibleSupplementaryViews(ofKind: UICollectionView.elementKindSectionHeader)[0] as! UICollectionReusableView
I've used above method to get current header, and successfully updated subviews on it.
Here's what I did to update only the section headers that are currently loaded in memory:
Add a weakToStrong NSMapTable. When you create a header, add the header as the weakly held key, with the indexPath object. If we reuse the header we'll update the indexPath.
When you need to update the headers, you can now enumerate the objects/keys from the NSMapTable as needed.
#interface YourCVController ()
#property (nonatomic, strong) NSMapTable *sectionHeaders;
#end
#implementation YourCVContoller
- (void)viewDidLoad {
[super viewDidLoad];
// This will weakly hold on to the KEYS and strongly hold on to the OBJECTS
// keys == HeaderView, object == indexPath
self.sectionHeaders = [NSMapTable weakToStrongObjectsMapTable];
}
// Creating a Header. Shove it into our map so we can update on the fly
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
PresentationSectionHeader *header = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:#"presentationHeader" forIndexPath:indexPath];
// Shove data into header here
...
// Use header as our weak key. If it goes away we don't care about it
// Set indexPath as object so we can easily find our indexPath if we need it
[self.sectionHeaders setObject:indexPath forKey:header];
return header;
}
// Update Received, need to update our headers
- (void) updateHeaders {
NSEnumerator *enumerator = self.sectionHeaders.keyEnumerator;
PresentationSectionHeader *header = nil;
while ((header = enumerator.nextObject)) {
// Update the header as needed here
NSIndexPath *indexPath = [self.sectionHeaders objectForKey:header];
}
}
#end
This question is very old but a simple way to do it is to just set a delay that covers the time your view is animating and disabling the animation while you update the view...usually a delete or insert takes about .35 seconds so just do:
delay(0.35){
UIView.performWithoutAnimation{
self.collectionView.reloadSections(NSIndexSet(index: 1))
}
My problem arose when frame sizes for the supplementary views changed upon invalidating the layout. It appeared that the supplementary views were not refreshing. It turns out they were, but I was building the UICollectionReusableView objects programmatically, and I was not removing the old UILabel subviews. So when the collection view dequeued each header view, the UILabels would pile up, causing erratic appearance.
The solution was to build each UICollectionReusableView completely inside the viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath method, starting by a) removing all subviews from the dequeued cell, then b) getting the frame size from the item's layout attributes to allow adding the new subviews.
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
yourClass *header = (yourClass *)[collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:#"identifier" forIndexPath:indexPath];
[[header viewWithTag:1] removeFromSuperview]; // remove additional subviews as required
UICollectionViewLayoutAttributes *attributes = [collectionView layoutAttributesForSupplementaryElementOfKind:kind atIndexPath:indexPath];
CGRect frame = attributes.frame;
UILabel *label = [[UILabel alloc] initWithFrame: // CGRectMake based on header frame
label.tag = 1;
[header addSubview:label];
// configure label
return header;
}
I have got a Perfect solution:
let footerView = self.collectionView.visibleSupplementaryViews(ofKind: UICollectionView.elementKindSectionFooter)
Now you can access all subview of footerView by using:
footerView[0].subviews[0]
If you have label in your footerView then :
let label: UILabel = footerView[0].subviews[0] as? UILabel ?? UILabel()
Final Step:
label.text = "Successfully Updated Footer."
if let footerView = collectionView.subviews.first(where: {$0 is LoadingFooterCell}) as? LoadingFooterCell {
footerView.isLoading = .loading
}
I want to implement pull-down-to-refresh in a UICollectionViewController under iOS 6. This was easy to achieve with a UITableViewController, like so:
UIRefreshControl *refreshControl = [[UIRefreshControl alloc] init];
[refreshControl addTarget:self action:#selector(startRefresh:)
forControlEvents:UIControlEventValueChanged];
self.refreshControl = refreshControl;
The above implements a nice liquid-drop animation as part of a native widget.
As UICollectionViewController is a "more evolved" UITableViewController one would expect somewhat of a parity of features, but I can't find a reference anywhere to a built-in way to implement this.
Is there a simple way to do this that I'm overlooking?
Can UIRefreshControl be used somehow with UICollectionViewController despite the header and docs both stating that it's meant to be used with a table view?
The answers to both (1) and (2) are yes.
Simply add a UIRefreshControl instance as a subview of .collectionView and it just works.
UIRefreshControl *refreshControl = [[UIRefreshControl alloc] init];
[refreshControl addTarget:self action:#selector(startRefresh:)
forControlEvents:UIControlEventValueChanged];
[self.collectionView addSubview:refreshControl];
That's it! I wish this had been mentioned in the documentation somewhere, even though sometimes a simple experiment does the trick.
EDIT: this solution won't work if the collection is not big enough to have an active scrollbar. If you add this statement,
self.collectionView.alwaysBounceVertical = YES;
then everything works perfectly. This fix taken from another post on the same topic (referenced in a comment in the other posted answer).
I was looking for the same solution, but in Swift. Based on the above answer, I have done the following:
let refreshCtrl = UIRefreshControl()
...
refreshCtrl.addTarget(self, action: "startRefresh", forControlEvents: .ValueChanged)
collectionView?.addSubview(refreshCtrl)
Not forgetting to:
refreshCtrl.endRefreshing()
I was using Storyboard and setting self.collectionView.alwaysBounceVertical = YES; did not work. Selecting the Bounces and Bounces Vertically does the job for me.
The refreshControl property has now been added to UIScrollView as of iOS 10 so you can set the refresh control directly on collection views.
https://developer.apple.com/reference/uikit/uiscrollview/2127691-refreshcontrol
UIRefreshControl *refreshControl = [UIRefreshControl new];
[refreshControl addTarget:self action:#selector(refreshControlAction:) forControlEvents:UIControlEventValueChanged];
self.collectionView.refreshControl = refreshControl;
mjh's answer is correct.
I ran into the issue where if the the collectionView.contentSize was not larger then the collectionView.frame.size, you can not get the collectionView to scroll. You can not set the contentSize property either (at least I couldn't).
If it can't scroll, it won't let you do the pull to refresh.
My solution was to subclass UICollectionViewFlowLayout and overide the method:
- (CGSize)collectionViewContentSize
{
CGFloat height = [super collectionViewContentSize].height;
// Always returns a contentSize larger then frame so it can scroll and UIRefreshControl will work
if (height < self.collectionView.bounds.size.height) {
height = self.collectionView.bounds.size.height + 1;
}
return CGSizeMake([super collectionViewContentSize].width, height);
}
I've tried to get this app going but I don't know how to go about it. I have tried googling for days getting a good answer but to no avail. Therefor I turn to you.
I want to have a typical database (sql or core data) with all data collected. Then display first criteria in a tableview, pass data to next tableview, and in the third tableview display cells depending on the two choices made previously (like: where (x=1 & y=2) then display cells ). Finally get a detailview where I can load optional data from the database.
Any which way you can help or point me in any direction would be great.
//KeLLoGsX
RayWenderlich Tutorials has a number of tutorials that might apply.
More specifically, when a user selects a row in a view use the prepareForSegue method to set a property on the new view indicating the selection so you can taylor the new view accordingly. For example:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([[segue identifier] isEqualToString:#"editTemplate"]) {
[[segue destinationViewController] setManagedObjectContext:self.managedObjectContext];
NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
self.selectedTemplate = [self.fetchedResultsController objectAtIndexPath:indexPath];
[[segue destinationViewController] setSelectedTemplate:self.selectedTemplate];
}
if ([[segue identifier] isEqualToString:#"returnToNotes"]) {
// do nothing special
}
}
The segue identifier like "editTemplte" are set in storyboard by selecting the segue and using the attributes inspector to name them.