I am trying to write the following objective-c code in robovm:
(NSIndexPath *)indexPath = ...;
cell.textLabel.text = [tableData objectAtIndex:indexPath.row];
However, when I look thru RoboVM's calls for NSIndexPath here:
https://github.com/robovm/robovm/blob/e60579613140f4a6d48f108042633fbf17b9c289/cocoatouch/src/main/java/org/robovm/apple/foundation/NSIndexPath.java
or by scrolling thru Eclipse's options, I don't see anything corresponding to row. What can I do?
I have no experience with RoboVM. However, indexPath.section and indexPath.row are just convenience methods/properties for
[indexPath indexAtPosition:0] // section
[indexPath indexAtPosition:1] // row
and the indexAtPosition: method is defined in the Java class.
Related
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;
Is there any particular reason why attempting to store and retrieve a value in an NSMutableDictionary using an NSIndexPath as a key might fail?
I originally attempted to do this in order to store an NSMutableDictionary of UITableViewCell heights (self.cellHeights) for a UITableView. Each time you tapped a UITableViewCell, that cell would either expand or contract between two different heights based on the value stored in the NSMutableDictionary for that particular indexPath:
- (CGFloat)tableView:(UITableView *)tableView
heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSNumber *heightNSNumber = [self.cellHeights objectForKey:indexPath];
if (!heightNSNumber)
{
heightNSNumber = [NSNumber numberWithFloat:100.0];
[self.cellHeights setObject:heightNSNumber forKey:indexPath];
}
return [heightNSNumber floatValue];
}
- (void)tableView:(UITableView *)tableView
didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
[tableView deselectRowAtIndexPath:indexPath animated:YES];
NSNumber *heightNSNumber = [self.cellHeights objectForKey:indexPath];
if (!heightNSNumber)
{
heightNSNumber = [NSNumber numberWithFloat:100.0];
[self.cellHeights setObject:heightNSNumber forKey:indexPath];
}
if ([heightNSNumber floatValue] == 100.0)
{
[self.cellHeights setObject:[NSNumber numberWithFloat:50.0]
forKey:indexPath];
} else {
[self.cellHeights setObject:[NSNumber numberWithFloat:100.0]
forKey:indexPath];
}
[tableView beginUpdates];
[tableView endUpdates];
}
For reasons unknown to me, getting the cell height within tableView:didSelectRowAtIndexPath: via [self.cellHeights objectForKey:indexPath] works just fine. However, trying to get the cell height within tableView:heightForRowAtIndexPath: via [self.cellHeights objectForKey:indexPath] always returns nil because it seems that the indexPath used to store the height doesn't match the indexPath being used to fetch the cell height, even though they have the same values for indexPath.section and indexPath.row. Because of this, a new object for the "same" index path is added to self.cellHeights (as evident since self.cellHeights.count increases thereafter).
This does not happen when you store the cell heights in the NSMutableDictionary using the row ([NSNumber numberWithInteger:indexPath.row]) as the key...so that's what I'm doing for now, but I'd like to understand why indexPath isn't working as the key.
Although I'm late in the discussion, here's a quick and simple solution that will allow you to use NSIndexPath instances as dictionary keys.
Just recreate the indexPath by adding the following line:
indexPath = [NSIndexPath indexPathForRow:indexPath.row inSection:indexPath.section];
Voilà. tableView:heightForRowAtIndexPath: uses NSMutableIndexPath instances internally (as you would see with a breakpoint). Somehow those instances seem uncooperative with NSIndexPath when calculating hash keys.
By converting it back to an NSIndexPath, then everything works.
#Jean's answer seems acceptable, but this question has been answered in more detail here. In short, UITableView sometimes uses instances of NSMutableIndexPath instead of NSIndexPath and instances of these two classes are never equal because [NSMutableIndexPath class] != [NSIndexPath class]. The workaround is to always generate a key NSIndexPath for anything that relies on isEqual or hash, such as looking up dictionary keys:
- (NSIndexPath *)keyForIndexPath:(NSIndexPath *)indexPath
{
if ([indexPath class] == [NSIndexPath class]) {
return indexPath;
}
return [NSIndexPath indexPathForRow:indexPath.row inSection:indexPath.section];
}
There are several things that must be implemented for an object to work reliably as a key for NSDictionary, namely isEqual:, hash and Copyable protocol.
I am not very sure that NSIndexPath was ever intented to work as a key for dictionaries (because it was made to be an index for arrays).
My guess is that hash is not implemented correctly for different instances of the class. Also note that some of the table delegate methods are called with NSIndexPath and some with NSMutableIndexPath. That's probably making the difference.
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.
Could somebody explain what I'm doing wrong in attempting to insert a new UITableViewCell? I'm trying to insert a custom UITableViewCell, but it throws the following error: 'Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (1) must be equal to the number of rows contained in that section before the update (1), plus or minus the number of rows inserted or deleted from that section (1 inserted, 0 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out).'
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
if (section == 0)
return 1;
else if (section == 1)
return numberOfRows;
return 1;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"EditableCell";
EditableCell *editableCell = (EditableCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (editableCell == nil) {
editableCell = [[EditableCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
_myTextField = [editableCell textFieldCell];
if (indexPath.section == 0){
[_myTextField setPlaceholder:#"Menu Name"];
[_myTextField setReturnKeyType:UIReturnKeyNext];
}
else if (indexPath.section == 1){
[_myTextField setPlaceholder:#"Category"];
[_myTextField setReturnKeyType:UIReturnKeyNext];
}
else {
[_myTextField setPlaceholder:#"Category"];
[_myTextField setReturnKeyType:UIReturnKeyDone];
}
_myTextField.keyboardType = UIKeyboardTypeDefault;
_myTextField.delegate = self;
return editableCell;
}
-(BOOL)textFieldShouldReturn:(UITextField *)textField{
if (textField.returnKeyType == UIReturnKeyNext) {
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:1];
NSArray *array = [[NSArray alloc] initWithObjects:indexPath, nil];
[self.tableView insertRowsAtIndexPaths:array withRowAnimation:UITableViewRowAnimationTop];
numberOfRows = numberOfRows + 1;
[self.tableView reloadData];
}
}
You need to make sure that the number of rows returned in the method below now returns the correct number of rows.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
I am sure what is happening is that you are returning the same value here after your insert, whereas the runtime is expecting it to be one more than it was before you made the call to insert a row.
In a bit more detail, what is happening in MVC terms (Model/View/Controller) is this:
Your call to insertRowsAtIndexPaths is requesting that the Controller update the View with an additional row.
The Controller then does a sanity check to see if you have your sums right, so it calls:
tableView:numberOfRowsInSection
Now the controller knows what value this method returned last time (in your case, 1), and it also knows that you have requested to insert a row. There have been no delete calls, so it expects the next time it calls this method, the value should be (last time's value + rows inserted - rows deleted) = 2
If the Controller deems that you have things in order, it will then call cellForRowAtIndexPath (along with other methods) to get the actual cells for each of the rows in each section.
So for your problem, you need to keep track of the rows in your model - maybe in an array or an ivar with the count of rows available. Update your model by updaing this value as you add/delete rows before you make the call to insertRowsAtIndexPath, and then return this value when tableView:numberOfRowsInSection is called.
Additional tip:
If you wish to have your cell inserts/deletes to be animated, change your code to the below. Notice there is no call to reloadData anymore, instead the insert/reload is wrapped in begin/end update calls - The animated updates will occur after endUpdates due to the reloadSections call.
NSMutableIndexSet *sectionsToReload = [[NSMutableIndexSet alloc] init];
[sectionsToReload addIndex:1]; // Add sections as necessary
[self.tableView beginUpdates];
[self.tableView insertRowsAtIndexPaths:array withRowAnimation:UITableViewRowAnimationTop];
[self.tableView reloadSections:sectionsToReload withRowAnimation:UITableViewRowAnimationNone];
[self.tableView endUpdates];
Check out the WWDC 2010 video from Apple, "Mastering Table Views" - explains everything really nicely, regarding using insertRowsAtIndexPaths and associated methods.
HTH,
Stretch
After you attempt to insert a new cell, your datasource must contain the number of original cells (1) plus the "extra" cell you are inserting (1) for a total of 2. So your tableView:numberOfRowsInSection: must return 2.
The error message indicated that tableView:numberOfRowsInSection: returned 1.
Update your datasource so that it returns this "extra" cell.
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];
}