I am using UICollectionView and my app crashes because I have odd number of items in my list but while I need to tow the items in section.
This is my the numbet of items in every section:
(NSInteger)collectionView:(UICollectionView *)view numberOfItemsInSection:(NSInteger)section
{
return 2;
}
Here is the problem:
In my list i have 3 items and when the objectAtIndex is 3 the app crashes
MSCoupon *coupon = [list objectAtIndex:indexPath.section * 2 + indexPath.row];
Do you have any solution for me?
This is happening because collection view is trying to access the 2nd element of 2nd section. which resulting in crash because your formula creating index 3.
For second element of section section Your formula
indexPath.section * 2 + indexPath.row
gives
1*2 + 1 = 3
Since your array have 3 element only it will through exception when you try to access fourth element.(array index start with 0).
In Collection view delegate you write this formula. leave rest of your code un-touch it should work
(NSInteger)collectionView:(UICollectionView *)view numberOfItemsInSection:(NSInteger)section {
return (list.count/(section + 1)) >= 2? 2: 1;
}
My solution is as follows:
- (NSInteger)collectionView:(UICollectionView *)view numberOfItemsInSection:(NSInteger)section
{
//return 2;
return [list count];
}
and:
- (NSInteger)numberOfSectionsInCollectionView: (UICollectionView *)collectionView
{
//return [list count]/2;
return 1;
}
Do you have a better advice for me?
Related
This is more of a math problem than anything else. What I have is a dynamic array object in which I store user photos.
arryData = [[NSArray alloc] initWithObjects:#"pic1.png", #"pic2.png", #"pic3.png", #"pic4.png", #"pic5.png", #"pic6.png",#"pic7.png", #"pic8.png",nil];
This array can have any amount of objects in it e.g 8 or 20 or 100. In my table view I have created 4 UIImageViews per row by adding them to cell.contentview. So if lets say
if arryData has 3 objects then I want UITable to create 1 row
if arryData has 4 objects then I want UITable to create 1 row
if arryData has 5 objects then I want UITable to create 2 rows
if arryData has 8 objects then I want UITable to create 2 rows
if arryData has 10 objects then I want UITable to create 3 rows
.... and so on
So how do I do this for N number of objects in my arryData?
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
//NSLog(#"Inside numberOfRowsInSection");
//return [arryData count];
//Cannot think of a logic to use here? I thought about dividing [arryData count]/4 but that will give me fractions
}
Picture is worth a thousand words.
So basically you need to divide by four, rounding up. Since integer division in Objective-C truncates (rounds toward zero), you can round up by doing this:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return (arryData.count + 3) / 4;
}
In general, to make integer division (with positive integers) round up, you add the denominator-1 to the numerator before dividing.
If you have defined a constant for the number of images per row, use it. For example:
static const int kImagesPerRow = 4;
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return (arryData.count + kImagesPerRow - 1) / kImagesPerRow;
}
For the row count, divide by the number of images and round up:
rowCount = ceilf([arryData count] / 4.0);
I suppose you have only one section so:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
NSInteger photoNumber = [yourDataSource count];
if(photoNumber % numberOfPhotosOnRow == 0) {
return photoNumber/numberOfPhotosOnRow;
}
else {
return photoNumber/numberOfPhotosOnRow + 1;
}
}
I had to create something similar for an application I wrote a little while back(it seems you want to include 4 images per cell)`
if (tableView == yourTableView)
{
int rows = [yourArray count];
int rowsToReturn = rows / 4;
int remainder = rows % 4;
if (rows == 0) {
return 0;
}
if (rowsToReturn >0)
{
if (remainder >0)
{
return rowsToReturn + 1;
}
return rowsToReturn ;
}
else
return 1;
}`
How would I be able to customize the amount of cells in each tableview group? Basically, I need 2 cells in the first group, 4 cells in the second group, and one cell in the third. I can't seem to find anything, which is odd, unless I'm calling it the wrong thing. Thanks in advance. :)
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
if (section == 0)
return 2;
else if (section == 1)
return 4;
else if (section == 2)
return 1;
}
Number of cells in each table section is specified in table's data source tableView:numberOfRowsInSection: method. Somewhat dummy example for your case:
- (int) numberOfSectionsInTableView:(UITableView*)tableView{
return 3;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
int numbers[] = {2,4,1};
return numbers[section];
}
I need to load 15 records initially and then when the user clicks on the show more row of the cell, i need to load the next 20 or available records in my tableview. I am looking at this question posted in SO.
This functionality can be seen in appStore too. Where you load the next number of records.
Here the solution is;
`- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return self.numberOfRowsVisible;
}
-(void)moreButtonClickAction {
if (self.numberOfRowsVisible < self.maxNumberOfRows)
self.numberOfRowsVisible = MIN(self.numberOfRowsVisible + 10, self.maxRows);
[self.tableView reloadData];
}
I initialized and hard coded the value in the viewDidLoad for numberOfRowsVisible as 15.
self.numberOfRowsVisible=[NSNumber numberWithInt:15];
in numberOfRowsInSection - i am not sure if this is correct.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return MIN([self.arrayRecords count], 15);
}
in the moreButtonClickAction
-(void)moreButtonClickAction {
if (self.numberOfRowsVisible < [self.arrayRecords count])
self.numberOfRowsVisible = MIN(self.numberOfRowsVisible + 15, [self.arrayRecords count]);
[self.tableView reloadData];
}
This is how i edited my code to suit the above suggestion left in SO. but this is not working. There seems to be some issue with MIN. I am not in MAC at the moment, so i can't remember the exact warning/error i got. So could someone kindly help me out.
1) Don't use an NSNumber object, a plain integer will do.
2) Why not just have an integer variable that shows the current number of rows that you want to display, and initialize with 15, and keep it in your class instance.
3) You don't even have to use MIN:
return [self.arrayRecords count] < self.numberOfRowsVisible ? [self.arrayRecords count] : self.numberOfRowsVisible;
You have to use MAX instead of MIN if you want to show all possible entries.
numberOfRowsInSection should return an integer.
self.numberOfRowsVisible is not an integer.
viewDidLoad:
self.numberOfRowsVisible=15;
main implementation:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return self.numberOfRowsVisible;
}
-(void)moreButtonClickAction {
if (self.numberOfRowsVisible < [self.arrayRecords count]) {
self.numberOfRowsVisible += 15;
if (self.numberOfRowsVisible > [self.arrayRecords count]) {
self.numberOfRowsVisible = [self.arrayRecords count];
}
}
[self.tableView reloadData];
}
off the top of my head, code could do with re-factoring.
All,
I have a grouped UITableView with a possible total of 3 sections. There could be 1, 2 or 3.
My issue is that for each section I use a different header & footer view. I am choosing which header/footer to show by checking the section #.
This obviously does not work, as section 0 does not always represent what 'header' 0 shows.
Example:
Header #0 = "Game in progress". But no games in progress are returned from the database. Only 'Games Ended" exist. Therefore section 0 would be all 'games ended'. I don't want 'Games Ended' to use the 'Games in Progress' header.
I can't find a way to check the section value, and not the number.
To put it simply, I would like to be able to show section header #3 for section name #3, even if section name #3 is section #0.
I know this seems trivial, and is probably simple... but I am stuck. Any help is appreciated.
Thanks.
----- CODE -----
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return [[fetchedResultsController_ sections] count];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
id <NSFetchedResultsSectionInfo> sectionInfo = [[fetchedResultsController_ sections] objectAtIndex:section];
return [sectionInfo numberOfObjects];
}
- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section {
if(section == 0)
{
return 50.0f;
}
else if (section == 1)
return 50.0f;
else
return 50.0f;
}
- (CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section {
if(section == 0 )
{
return 50.0f;
}
else if (section == 1)
return 5.0f;
else
return 80.0f;
}
- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
if(section == 0)
{
return headerView1;
}
else if (section == 1)
return headerView2;
else
return headerView3;
}
- (UIView *)tableView:(UITableView *)tableView viewForFooterInSection:(NSInteger)section {
if(section == 0)
{
return footerView1;
}
else if (section == 1)
return footerView2;
else
return footerView3;
}
Obviously, deciding which header / footer to show by checking the section # is wrong (this is bad MVC). For a solution to your problem, it would be better to see some actual code, although I think I can suggest something in general:
The sections that you show are taken out of some data source - an array, a dictionary or some other collection (this is the same collection you use to determine, for example, the return value for the numberOfSectionsInTableView: delegate method. If you haven't done so already, you should incorporate these data instances into some object that contains the data itself (this is the data that you normally need for displaying the cell/header/footer elements along with the actual data values) - In this object, add an additional "HeaderType" enumerated value, so that each object "knows" how it is supposed to be displayed. This way your MVC is perfect: You have your data stored in a collection of custom objects, your controller knows how to display the data by it's type and of course your view shows the data properly based on the controller's instructions.
Here is an example of an enumeration that could help:
typedef enum {
kHeaderTypeGameProgress,
kHeaderTypeGameStats,
kHeaderTypeGameDate
} HeaderType;
In your "viewForHeader" or "viewForFooter" methods, just add a switch type to check the data's HeaderType and create a view accordingly. Hope I helped, good luck!
It seems that in your cellForRowAtIndexPath, you must already have some logic that decides what group to show data from, maybe something like:
NSArray *group;
int section = indexPath.section;
if (![gamesInProgress count]) section++;
switch (section) {
case 0:
group = gamesInProgress;
break;
case 1:
group = finishedGames;
break;
// etc.
}
In your viewForHeaderInSection, write similar code that sets a NSString instead of NSArray.
I am implementing a table index view and amazed to see how my table indexes are working even without implementing:
- (NSInteger)tableView:(UITableView *)tableView sectionForSectionIndexTitle:(NSString *)title atIndex:(NSInteger)index method.
I have only implemented:
- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView
Strangely, when I am running in breakpoints, Once i click on any of the index values my
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
method is getting called.
Any clue why this is so happening and what is the significance of sectionForSectionIndexTitle method then.
if you have a list of all letters in alphabet and your list only contains some entries, you could use the following code:
//Asks the data source to return the index of the section having the given title and section title index.
- (NSInteger)tableView:(UITableView *)tableView sectionForSectionIndexTitle:(NSString *)title atIndex:(NSInteger)index {
if (tableView == self.searchDisplayController.searchResultsTableView || self.searchBar.text.length > 0)
{
return 0;
}
else
{
//direct - firsttime match
if([self.realMIndexArray containsObject:title]) {
NSInteger count = 0;
for(NSString *character in self.realMIndexArray)
{
if([character isEqualToString:title]){
return count;
}
count ++;
}
}
else {
//take next higher letter from alphabet and check if its contained in the "available letters list"
//if not, select last entry of list
for(int i = [self.indexArray indexOfObject:title] + 1; i < [self.indexArray count]; i++) {
NSString* character = [self.indexArray objectAtIndex:i];
if([self.realMIndexArray containsObject:character]) {
return [self.realMIndexArray indexOfObject:character];
}
}
return [self.realMIndexArray count] - 1;
}
return 0;// in case of some eror donot crash d application
}
}
realMIndexArray count == letters really existing in list
indexArray = list of all letters in alphbeth.
hope this helps someone (took me a little bit of time to figure it out)
Any clue why this is so happening
Yes. When you tap (you do not click on an iPhone) on a table's index, the underlying table view will want to jump to that section, and the cells in that section. In order to do that, it has to ask the data source for those cells so it can render them on the screen.
what is the significance of
sectionForSectionIndexTitle method
then.
The documentation for tableView:sectionForSectionIndexTitle:atIndex: (which is an optional method in the UITableViewDataSource protocol) says:
Asks the data source to return the
index of the section having the given
title and section title index.
and
You implement this method only for
table views with a section index
list—which can only be table views
created in the plain style
(UITableViewStylePlain).
Does this apply for your UITableView? In other words, are you using a grouped table view style?