I have created sample application that insert 12 rows in tableview.And inserted fine.When after inserted my rows i dont want any changes in text during scrolling of tableview.So i checked with indexpath row has value of UITableViewCell , if it has values means return that cell otherwise we created new UITableViewCell.
My sample code is below
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
// Customize the number of rows in the table view.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
NSLog(#"GlobalCount = %d",GlobalCount);
return GlobalCount;
}
- (UITableViewCell *)tableView:(UITableView *)tv cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *obj = (UITableViewCell*)[tableView cellForRowAtIndexPath:indexPath];
if(obj!=nil)
{
NSLog(#"cell indexpath row = %d",indexPath.row);
NSLog(#"cell text = %d",obj.textLabel.text);
return obj;
}
else {
NSLog(#"obj==nil");
}
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tv dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
}
if([DataTable count]>0)
cell.textLabel.text = [DataTable objectAtIndex:0];
// Configure the cell.
return cell;
}
What my objective is , i dont want update any text (or UITableViewCell)for already created indexpath rows(of cell).So i can check this in cellForRowAtIndexPath , but it always return nil.If i am missing anything ?
I checked using this line
UITableViewCell *obj = (UITableViewCell*)[tableView cellForRowAtIndexPath:indexPath];
if(obj!=nil)
Plz help me?
Thanks in advance......
Let the table view decide id it need to update the cell or not. Just remove all the firsdt part of your code and everything will run smoothly.
Don't hesitate to read the UITableView doc.
Related
I am new in iPhone application development. I am currently working on XML parsing. I am extracting records from an xml file and storing it in an mutable array. I have a table view and i am loading the table view from that mutable array. I get 18 rows in the table view which i found by debugging. The problem is when i scroll down upto 10 rows it moves well but as 10th row appears the app crashes. i get the error of EXC_BAD_ACCESS. Here is my code where the cell gets loaded. Thanks.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"cell"];
if(cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"cell"];
Location *record = [[Location alloc] init];
record = [[parse locationarr] objectAtIndex:indexPath.row];
cell.textLabel.text = record.locationname;
return cell;
}
}
There are some misstakes in the code you post, first you only return a cell is the table isn't return a cell for dequeueing
Thus changing you code likewise will solve that problem:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"cell"];
if(cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"cell"];
}
Location *record = [[Location alloc] init];
record = [[parse locationarr] objectAtIndex:indexPath.row];
cell.textLabel.text = record.locationname;
return cell;
}
Also having to alloc and init a Location every time is very costly, it's better to have a Location with in the class that you call every time a cell is needed.
Beter yet is to just grab the data for the cell only and not do any lengthy method in the tableVieew:cellForRowAtIndexPath: method.
your mistake is " return cell" which is written in inside the if condition take it outside also row title label text set out side condition.like this way..
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"cell"];
if(cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"cell"];
Location *record = [[Location alloc] init];
}
else
{
// get record object here by tag.
}
record = [[parse locationarr] objectAtIndex:indexPath.row];
cell.textLabel.text = record.locationname;
return cell;
}
You need to write this snippet
`record = [[parse locationarr] objectAtIndex:indexPath.row];
cell.textLabel.text = record.locationname;`
out of if block.
Enjoy Programming!!
I have a table with a few rows, and the place holder text for all is the same. How can I programmatically change the placeholder text of only the first one?
Thanks!
You need to run an if statement to check the index of the cell. 0 is the first index, so you would need to check to see if the row is 0.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
if (indexPath.row == 0)
cell.textLabel.text = #"First Cell";
else
cell.textLabel.text = #"Not First Cell";
}
In order to access your cell AFTER the cell was created/reused, try the - (UITableViewCell *)cellForRowAtIndexPath:(NSIndexPath *)indexPath method of your uitableview object! See the following Apple doc for a detailed elaboration on this method.
Note:
Return Value
An object representing a cell of the table or nil if the cell is not
visible or indexPath is out of range.
Hey I'm having trouble trying to figure this one out. UITableView has a method [tableView reloadSections:(NSIndexSet *) withRowAnimation:(UITableViewRowAnimation)] now according to the Apple docs this method takes in an NSIndexSet object and reloads what ever section specified by the index set. The problem is even though im only sending in one section to this method it ends up reloading all the sections and i can't understand why this is happening. Any help will be greatly appreciated
Even if you try reloading only a section, you must also provide the populating process section by section:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"DetailViewCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:CellIdentifier] autorelease];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
}
if (indexPath.section == 0){
//blablabla
cell.textLabel = blabla
}
else if (indexPath.section == 1){
///blablabla
cell.textLabel = blabla2
}
return cell;
}
... because reloading the table (is it only a section or the whole table) wil call the method above
So I don't know how this is happening, or how to fix it, but I am having an issue of my UISearchDisplayController's plain tableView displaying search results with a grouped cell.
I have a dataSource array with a few names, a tableData array that iterates through the dataSource array and adds any entries that fit the searchText, and then depending on which tableView it is, I reload the tableView with the appropriate dataSource...
Ideas anyone?
Code:
- (NSInteger)tableView:(UITableView *)aTableView numberOfRowsInSection:(NSInteger)section {
// Return the number of rows in the section.
int count = 0;
if(aTableView == self.tableView){
count = [userTableData count]==0?1:[userTableData count];
}else{
count = [tableData count];
}
return count;
}
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
return #"Users";
}
- (UITableViewCell *)tableView:(UITableView *)tView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"CellIdentifier";
// Dequeue or create a cell of the appropriate type.
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
cell.accessoryType = UITableViewCellAccessoryNone;
}
if(tView == self.tableView){
if([userTableData count] == 0){
cell.textLabel.text = #"Please select a user";
}else{
cell.textLabel.text = [userTableData objectAtIndex:indexPath.row];
}
}else{
cell.textLabel.text = [tableData objectAtIndex:indexPath.row];
}
return cell;
}
And then as the search is entered, matching strings are added to the tableData array
assign tags to the UITableView and hide the grouuped tableView while searching
In the documentation for UISearchDisplayController about the searchResultsTableView property, it says
Discussion:
This method creates a new table view if one does not already exist.
So what you could try is create your own UITableViewwhen you set up the UISDC, explicitly making it plain:
UITableView *searchTableView = [[UITableView alloc] initWithFrame:CGRectZero
style:UITableViewStylePlain];
searchDisplayController.searchResultsTableView = searchTableView;
Can anyone tell me that how to remove all rows of a tableView
Clear the datasource (for example [dataSourceMutableArray removeAllObjects]) and reload the table ([tableView reloadData])
I think you can remove all values in dataSource of tableView? Then reload the tableView
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 0;
}
// Customize the number of rows in the table view.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return 0;
}
or specify return nil; instead of return cell; in cellForRowAtIndextPath function
or you can remove all values in array in cellForRowAtIndexPath like this
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
// Configure the cell.
// remove below line
//cell.textlabel.text=[array objectAtIndex:indextPath];
return cell;
}