I have the following entry that updates a labels text with the value:
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *row = [tableView dequeueReusableCellWithIdentifier:#"TICKET_ITEM"];
UILabel *itemDiscount = (UILabel *)[row viewWithTag:502];
itemDiscount.text = [[arrayOfItem objectAtIndex:indexPath.row]TICKET_ITEM_DISCOUNT];
return row;
}
My problem is that after the fact I have button that allows for setting the discount (which is initially 0). After adjusting a slider I want to be able to take that discount % and update itemDiscount.text with the new value. I figure the way I need to do this is to update the arrayOfItem TICKET_ITEM_DISCOUNT entry and then use reloadData. But how do I update just the single item in the array?
Check out Apple's documentation on NSArray.
There are a variety of methods that could solve your problem.
indexOfObject:
or
indexOfObjectPassingTest:
spring to mind.
To edit an NSArray you'll need to make a mutable copy of the array then assign it back again:
NSMutableArray *temp = [arrayOfItem mutableCopy];
//update your value here
arrayOfItem = temp;
Related
I have project where user can add some Items to TableView. My data source for this TableView are objects with 2 properties NSString * nameOfItem and NSNumber * numberOfItem. Is any possibility to check my NSMutableArray if it contain string #"someString" as property nameOfItem and if yes than change numberOfItem +1 ?
UPDATE:
I try to do it with for(...in...) but it works just when i have only one object in my NSMutableArray. If i have more objects there it create one new object and than change value to ++ on old one:
Here is some code what i tried:
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
NSString*nameToCheck = [NSString stringWithFormat:#"%#", [self.ivc.objects objectAtIndex:indexPath.row]];
for (Items *itemNamed in self.ivc.shoppingList.items) {
if ([itemNamed.nameOfItem isEqualToString:nameToCheck]) {
[itemNamed setNumberOfItem:[NSNumber numberWithInt:[itemNamed.numberOfItem integerValue]+1.0]];
} else {
Items *item = [Items new];
[item setNameOfItem:name];
[item setNumberOfItem:#(1)];
[self.ivc.shoppingList.items insertObject:item atIndex:0];
}
I want to create new one only if is not yet in that list.
Any help appreciated.
I don't know something like this but you can use a NSDictionary instead of NSArray using the name property as a key. And if you don't want to do that, you can sort the array and make a binary search for element.
So I've been looking for an answer to this interesting issue I came across but haven't had very much luck. Basically I have a UITableView preloaded on initial app launch with a few objects using CoreData, and the ability for the user to add more.
I allow deleting of cells in the table, except for the items I have initial pre-loaded. So I perform a check in my canEditRowAtIndexPath method and return NO if the selected item is one of these pre-loaded items. Everything works great until I scroll down far enough for one of the items to be offscreen, and then when it snaps back the item that shouldn't be editable, is now editable.
I'm fairly new to iOS development, so I'm hoping this is a rather amateur issue - but I can't seem to find the answer.
Any help is appreciated.
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
DataLayer *dl = [DataLayer alloc];
// Get all items from Favorites
NSArray *results = [dl FetchAll:#"Favorites"];
// Get currently selected cell properties
FavoritesTableCell *selectedCell = [tableView cellForRowAtIndexPath:indexPath];
Favorites *fav = [Favorites alloc];
NSMutableArray *genItems = [[NSMutableArray alloc] init];
// Get only records that are default app items
for(int a = 0; a < [results count]; a++){
fav = [results objectAtIndex:a];
if ([fav.generic isEqualToNumber:[NSNumber numberWithInt:1]]) {
[genItems addObject:fav];
}
}
// Loop through default items to determine if editable
for (int i = 0; i < [genItems count]; i++) {
fav = [genItems objectAtIndex:i];
if ([fav.title isEqualToString:[selectedCell.nameLabel text]]) {
return NO;
}
}
return YES;
}
The root of the problem is that this method is basing it's answer on the content of a table view cell (selectedCell) rather than the model.
Table views reuse cells. As they are scrolled off the view, the "new" cells that appear are really the same object's that just disappeared on the other side of the table. So that selectedCell is not a good reference for a question that ought to be put to your model.
The code needs to be structured like this:
Your model is a NSMutableArray that starts with a few items you add. You need to know which items are originals, not to be removed:
#property (nonatomic, strong) NSMutableArray *favorites;
#property (nonatomic, assign) NSMutableArray *genericFavorites;
// at init, imagine these strings are your preloaded core data
[self.genericFavorites addObject:#"generic favorite object a"];
[self.genericFavorites addObject:#"generic favorite object b"];
[self.favorites addItemsFromArray:self.genericFavorites];
You'll use self.favorites as your model, that is when table view asks numberOfRowsInSection, you'll answer self.favorites.count. In cellForRowAtIndexPath, you'll lookup the item in self.favorites[indexPath.row] and configure the cell with data from that object. self.genericFavorites just helps you remember which objects are original, not added by the user.
If the order remains fixed, then your canEditRow logic is simple:
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
return indexPath.row >= self.genericFavorites.count;
}
But if, as maybe your code implies, the user can reorder these items, then your canEditRow has more work to do, but it can do that work without reference to the table cells (which as I indicated, are unreliable):
// get the object at indexPath.row from our model. Answer NO if that object was preloaded
// from the app (if genericFavorites containsObject:), YES otherwise
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
Favorite *favorite = self.favorites[indexPath.row]; // this is your model after user has edited, reordered, etc
return ![self.genericFavorites containsObject:favorite];
}
Currently I fill a UITableView using this method:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"CharNameCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
MyObject *obj = (MyObject*)[self.characters objectAtIndex:indexPath.row];
cell.textLabel.text = obj.name;
return cell;
}
But what could one do if you had two different arrays from two different types and you wanted to display a property from each in the cells?
Pseudocode:
MyObject1
MyObject2
cellTextLabel.text = Myobject1.name;
cellTextLabel.text = MyObject2.name;
Assuming that each object has a name property. I know my syntax above isn't correct, but I think you should get the drift.
I would suggest then that you store all of your objects in an NSMutableArray. This will be your data model. Then you can just iterate through the array to display the data in the UITableView. If need be, use introspection to find out what kind of class your object is.
id currentObject = [myArray objectAtIndex:indexPath.row];
if ([currentObject isKindOfClass:[MyObject1 class]]){
//set properties or do stuff with MyObject1
}else if ([currentObject isKindOfClass:[MyObject2 class]]){
//do stuff with Object2
}
This is just one suggestion. There are many ways to do this, but it will all depend on your app and what kind of persistence you are using, etc. Hope this helps.
I'm having a problem adding an item to my tableView.
I used to initialize an empty tableView at the start of my App and get it filled with scanned items every time the tableView reappears and there is an item in my variable.
Initialization of the tableView:
NSMutableArray *array = [[NSMutableArray alloc] initWithObjects:nil];
self.listArray = array;
TableView Data Source:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
return [self.listArray count];
}
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
if(section == 0)
return #"Eingescannte Artikel:";
else
return nil;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"testCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
// Configure the cell...
NSUInteger row = [indexPath row];
cell.textLabel.text = [listArray objectAtIndex:row];//[NSString stringWithFormat:#"Das ist Zeile %i", indexPath.row];
return cell;
}
(Not the whole thing but the ones I changed)
As you may have seen I use an NSMutableArray to add items to my tableView.
So if an item ist scanned I'm adding it to my array like this:
[listArray insertObject:sharedGS.strEAN atIndex:0]; //using a shared Instance where I implemented my variable.
I also tried to use an variable to extend my Index every time a new Item is added, but it won't work both ways.
I'm quite new to programming so an not-too-hard-to-understand-answer would be quite nice ;)
If there's any information missing, feel free to ask.
/edit: Trying to specify my question: The data from the variable is written in a TableViewCell, but if I scan another one the other one is just being replaced. Not sure if it's a problem with my array or my tableView...
/edit No.2: Found out(thanks to fzwo) that my array isn't working correctly. It just doesn't grow by an addObject: or insertObject:atIndex: command. But I just don't get why... :(
All I'm doing: [listArray addObject:sharedGS.strEAN]; not that much space for errors in one simple line. Maybe I'm just too stupid to recognize what I'm doing wrong:D
You state that your problem is "adding an item to my tableView" , since you are adding the object to your array i am guessing the problem is that you are not reloading the table or that it is missing the dataSource binding.
You have not actually asked any question (even if you added info to "specify your question") so a wild guess, after
[listArray insertObject:sharedGS.strEAN atIndex:0];
put
[yourTableView reloadData];
Are you intentionally adding new items to the top of the table ? otherwise you could do
[listArray addObject:sharedGS.strEAN]; to add new items to the bottom
Otherwise it's worth noting that you are misusing dequeueReusableCellWithIdentifier, look at the example below for proper usage:
// Try to retrieve from the table view a now-unused cell with the given identifier
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier];
// If no cell is available, create a new one using the given identifier
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:MyIdentifier] autorelease];
}
I have a number of views with UITableViews and I'd like to quickly add code to each so that I can add a row with a simple label saying that there was no data to be shown.
Whats making things a little bit more complicated is that in some cases I'm using custom cells.
I don't want to have to change my populate data array functions, but I can't think of a way to add this feature to a lot of tables quickly.
Can anyone show me what to do ?
In the tableView:numberOfRowsInSection: data source method, get the number of rows as normal. Then, if the number is 0, return 1 instead. In the tableView:cellForRowAtIndexPath: method, perform the same test. If there is no data, use a different cell and set it up for your message.
The following example assumes that you have 1 section and that your data is an NSArray instance variable named theArray which contains strings.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
NSInteger num = theArray.count;
return (num ? num : 1);
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell;
if(theArray.count == 0) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:nil] autorelease];
cell.textLabel.text = #"No Data Found";
return cell;
}
// Normal processing here
}