App is crashing when NSMutableArray no Objects in iOS - ios

Question

I have four textfields like textfield1, textfield2, textfield3, textfield4 and one button. When I click on the button I am adding the textfield text to an NSMutableArray and populating in a tableview.
My code is:
- (void)buttonClick
{
NSMutableArray *array =[[NSMutableArray alloc]init];
[array addObject: textfield1.text];
[array addObject: textfield2.text];
[array addObject: textfield3.text];
[array addObject: textfield4.text];
}
Populating in table view using delegate methods
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [array count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
}
cell.textLabel.text =[array objectAtIndex:indexPath.row];
return cell;
}
The above code is working fine. But when I click on button without entering any data in the textfields, the app is crashing because the array is empty. How to solve this problem?

Answer 1

You can't add nil to an array.
[array addObject:textfield1.text ?: #""];
[array addObject:textfield2.text ?: #""];
[array addObject:textfield3.text ?: #""];
[array addObject:textfield4.text ?: #""];
This makes sure there are four items in the array (possibly empty strings).

Answer 2

Why crashes?
You can't add nil in array. It should have something inside of it.
-(void)buttonClick
{
NSMutableArray *array =[[NSMutableArray alloc]init];
if ([textfield1.text length]>0) {
[array addObject: textfield1.text];
}
if ([textfield2.text length]>0) {
[array addObject: textfield2.text];
}
if ([textfield3.text length]>0) {
[array addObject: textfield3.text];
}
}

Answer 3

Try this
-(void)buttonClick
{
NSMutableArray *array =[[NSMutableArray alloc]init];
if(textfield1.text.length > 0)
[array addObject: textfield1.text];
if(textfield2.text.length > 0)
[array addObject: textfield2.text];
if(textfield3.text.length > 0)
[array addObject: textfield3.text];
if(textfield4.text.length > 0)
[array addObject: textfield4.text];
}
Populating in table view using delegate methods
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [array count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
}
cell.textLabel.text =[array objectAtIndex:indexPath.row];
return cell;
}
if you have multiple text fields then:
//give tag value of each textfield from 100 to 150 or any any tag (i am considering 50 text fields)
for (int i=100; i<=150; i++) {
// self.view or use ur view on which u r addding textfield
id txtF = [self.view viewWithTag:i];
if([txtF isKindOfClass:[UITextField class]]) {
UITextField *txtField = (UITextField*)txtF;
if(txtField.text.length > 0) {
//Add ur object
}
}
}

Answer 4

you can check the textfields before putting an array wheather it has text or not if yes then put in the array only.

Answer 5

This line in the buttonClick method defined a local array variable:
NSMutableArray *array =[[NSMutableArray alloc]init];
It should be
array =[[NSMutableArray alloc]init];
Which is your instance variable array.