如何从NSDictionary获取NSDecimalNumber

Question

I want to set the value for Key1 as 10.00 itself rather than 10

            NSDictionary *dict = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:
                                 [NSDecimalNumber decimalNumberWithString:@"10.00"],
                                 [NSDecimalNumber decimalNumberWithString:@"10.19"],nil]
                                 forKeys:[NSArray arrayWithObjects:@"Key1",@"Key2",nil]];


            NSLog(@"Value For Key1 NSDecimalNumber %@",[dict valueForKey:@"Key1"]);
            NSLog(@"Value For Key1 float %f",[[dict valueForKey:@"Key1"] floatValue]);

            NSLog(@"Value For Key2 NSDecimalNumber %@",[dict valueForKey:@"Key2"]);
            NSLog(@"Value For Key2 float %f",[[dict valueForKey:@"Key2"] floatValue]);

This is the log that I get from the console

    2013-05-16 12:43:23.316 SampleTest[6569:19d03] Value For Key1 NSDecimalNumber 10
    2013-05-16 12:43:23.771 SampleTest[6569:19d03] Value For Key1 float 10.000000
    2013-05-16 12:43:24.263 SampleTest[6569:19d03] Value For Key2 NSDecimalNumber 10.19
    2013-05-16 12:43:25.195 SampleTest[6569:19d03] Value For Key2 float 10.190000

Can anyone help me out???

Thanks in advance..

Answer 1

If you just need a formatted string with precision for decimal values. You can use

NSString *str = [NSString stringWithFormat:@"%.2f",[[dict valueForKey:@"Key1"] floatValue]];
NSLog(@"str - %@",str);

str will always have the string with precision of 2 digits.

Hope this helps and is simple.

Answer 2

If I understand you correctly you want to control the output format of your NSDecimalNumber object.
Cocoa provides the NSNumberFormmatter class for that purposes. It allows you to customize the string representation of your number without modifying the actual value.

NSDecimalNumber is a good choice if you have to deal with numbers that require high precision. Eg when working with currencies.

I modified your sample to output a formatted version of the first value stored in the dict :

NSDictionary* dict = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:
                                                          [NSDecimalNumber decimalNumberWithString:@"10.00"],
                                                          [NSDecimalNumber decimalNumberWithString:@"10.19"],nil]
                                                 forKeys:[NSArray arrayWithObjects:@"Key1",@"Key2",nil]];
NSNumberFormatter* formatter = [[NSNumberFormatter alloc] init];
[formatter setNumberStyle:NSNumberFormatterDecimalStyle];
[formatter setAllowsFloats:YES];
[formatter setAlwaysShowsDecimalSeparator:YES];
[formatter setFormat:@"#,##0.00"];
NSString* formattedValue = [formatter stringFromNumber:[dict valueForKey:@"Key1"]];
NSLog(@"Value For Key1 %@",formattedValue);