Convert array of NSStrings to array of formatted NSNumbers - objective-c

Question

I have an array of strings called valuesArray containing values like this: 2913451.0938
I am trying to format those numbers so that I can display them like this: 2,913,451.09
Using the following code I am able to read the values from the array and convert them to NSNumbers (num), and I am also able to create a formatter to define how I want my numbers to be displayed (formatter).
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
[formatter setNumberStyle:NSNumberFormatterDecimalStyle];
[formatter setMaximumFractionDigits:2];
NSNumber *num = valuesArray[indexPath.row];
NSLog(#"num: %#",num);
NSLog(#"Formatter: %#",formatter);
NSString *forNum = [formatter stringFromNumber:num];
NSLog(#"FormattedNum: %#",forNum);
When I run the code and get to the line NSLog(#"FormattedNum: %#",forNum); I see that it prints null. What am I missing?

Answer 1

The problem in your code is that you retrieve an element from you array of strings valueArray but assign it to an NSNumber typed variable—while the object really is an NSString. When you pass it to the formatter it returns nil (even though it also might crash, it's just undefined behavior).
You have to convert the string to an NSNumber:
NSNumber *num = #([valuesArray[indexPath.row] doubleValue]);

Answer 2

I just checked this code with this value :
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
[formatter setNumberStyle:NSNumberFormatterDecimalStyle];
[formatter setMaximumFractionDigits:2];
NSNumber *num = #(2913451.0938);
NSLog(#"num: %#",num);
NSLog(#"Formatter: %#",formatter);
NSString *forNum = [formatter stringFromNumber:num];
NSLog(#"FormattedNum: %#",forNum);
It worked fine, no error what so ever as you mentioned.
See the Output :
2013-02-28 21:35:44.417 BrowserModal[4861:403] num: 2913451.0938
2013-02-28 21:35:44.418 BrowserModal[4861:403] Formatter: <NSNumberFormatter: 0x100160840>
2013-02-28 21:35:44.419 BrowserModal[4861:403] FormattedNum: 29,13,451.09
Please clean your target and re-build.
And
Make sure valuesArray[indexPath.row] returns a boxed NSNumber object.
Do as : #([valuesArray[indexPath.row] doubleValue]);