CODEWITHSUNDEEP
iosobjective-cexceptionuipickerview
fabdurso
fabdurso

Reputation: 2444

pickerViews crashes

Here is my code:

@synthesize pickerLetter, pickerNumber, pickerSymbol;


- (void)viewDidLoad {
 [super viewDidLoad];
 letters = [[NSArray alloc]initWithObjects:@"a", @"b", @"c", nil];
 numbers = [[NSArray alloc]initWithObjects:@"1", @"2", @"3", nil];
 symbols = [[NSArray alloc]initWithObjects:@"+", @"-", @"/", nil];
}

-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
 return 1;
}

-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
 if (pickerView == pickerLetter) {
    return letters.count;
 } else if (pickerView == pickerNumber){
    return numbers.count;
 } else {
    return symbols.count;
 }
}

-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
 if (pickerView == pickerLetter) {
    return [letters objectAtIndex:row];
 } else if (pickerView == pickerNumber){
    return [numbers objectAtIndex:row];
 } else {
    return [symbols objectAtIndex:row];
 }
}

This is giving me

Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 1 beyond bounds [0 .. 0]'

when I use the pickers in the Simulator.

The code that is causing the crash is

-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
 label.text = [NSString stringWithFormat:@"%@ %@ %@",[letters objectAtIndex:[pickerLetter selectedRowInComponent:0]],[numbers objectAtIndex:[pickerNumber selectedRowInComponent:1]],[symbols objectAtIndex:[pickerSymbol selectedRowInComponent:2]]];
}

Upvotes: 0

Views: 149

Answers (2)

rmaddy
rmaddy

Reputation: 318774

You've narrowed down your issue to this code:

-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    label.text = [NSString stringWithFormat:@"%@ %@ %@",[letters objectAtIndex:[pickerLetter selectedRowInComponent:0]],[numbers objectAtIndex:[pickerNumber selectedRowInComponent:1]],[symbols objectAtIndex:[pickerSymbol selectedRowInComponent:2]]];
}

But this line has several calls to objectAtIndex: so it's hard to know the exact issues. Plus this code is hard to read and impossible to debug. Start by splitting up this code as follows:

-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    NSInteger letterIndex = [pickerLetter selectedRowInComponent:0];
    NSString *letter = letters[letterIndex];
    NSInteger numberIndex = [pickerNumber selectedRowInComponent:1];
    NSString *number = numbers[numberIndex];
    NSInteger symbolIndex = [pickerSymbol selectedRowInComponent:2];
    NSString *symbol = symbols[symbolIndex];

    label.text = [NSString stringWithFormat:@"%@ %@ %@", letter, number, symbol];
}

Doing this you will be able to narrow down the real cause of your issue.

As you can see, the problem is that you are referencing the wrong component number from the pickerNumber and pickerSymbol. All three pickers only have 1 component so you need to select component 0 from all three pickers.

The needed code is:

-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    NSInteger letterIndex = [pickerLetter selectedRowInComponent:0];
    NSString *letter = letters[letterIndex];
    NSInteger numberIndex = [pickerNumber selectedRowInComponent:0];
    NSString *number = numbers[numberIndex];
    NSInteger symbolIndex = [pickerSymbol selectedRowInComponent:0];
    NSString *symbol = symbols[symbolIndex];

    label.text = [NSString stringWithFormat:@"%@ %@ %@", letter, number, symbol];
}

Avoid putting more than one or two method calls on a single line of code. It makes the code less readable and much harder to debug if there is a problem.

Upvotes: 2

Sucharu Hasija
Sucharu Hasija

Reputation: 1126

you are calling a wrong way to implement the method 

-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
 if (pickerView == pickerLetter) {
    return [letters objectAtIndex:row];
 } else if (pickerView == pickerNumber){
    return [numbers objectAtIndex:row];
 } else {
    return [symbols objectAtIndex:row];
 }
}

change it to 

-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
 if (component == 0) {
    return [letters objectAtIndex:row];
 } else if (component == 1){
    return [numbers objectAtIndex:row];
 } else {
    return [symbols objectAtIndex:row];
 }
}

Upvotes: -1

Related Questions