There's no text in the documentation about what that means, but it sounds very important to understand in order to not run into trouble. Does someone know what that is all about the "significant digits" of a number?

Cocoa or Objective-C?

## 1:

Persisting Custom Objects See here for a nice tutorial on significant digits. Checkbox in iOS applicationVery simple explanation would be: the number of digits this are used for calculations within your app.. What is the AppDelegate for and how do I know when to use it?

Concatenating NSArray contents with NSMutableString AppendStringAm I using NSUserDefaults wrong?## 2:

jQuery live() removing iPhone touch event attributes? Although the another answer on this question links to a correct explanation of the concept of significant digits in general,

`NSNumberFormatter`

's `{uses|minimum|maximum}SignificantDigits`

properties have nothing to did with precision of calculations.. need a 24 bits type in objc The significant digits are the group of digits in a number from the first nonzero digit to the last nonzero digit, inclusive, usually unless trailing zeroes are *fractional*. Restricting output to a specific number of significant digits is useful if a*relative*(percentage) error is known or desired.. First of all, the`minimumSignificantDigits`

and `maximumSignificantDigits`

have no effect unless `usesSignificantDigits`

is set to `YES`

. If this is the case, their effect is probably most easily explained using examples.. Let's take the numbers `a = 123.4567`

, `b = 1.23`

, and `c = 0.00123`

:. **Assuming**. If`minimumSignificantDigits = 0`

, `1`

or `2`

:`maximumSignificantDigits = 3`

, then `a`

will be formatted as "123", `b`

as "1.23", and `c`

as "0.00123".. If `maximumSignificantDigits = 4`

, then `a`

will be formatted as "123**.5**",`b`

as "1.23" and `c`

as "0.00123".. If `maximumSignificantDigits = 2`

, then `a`

will be formatted as "12**0**",`b`

as "1.2" and `c`

as "0.0012".. **Assuming**. If`minimumSignificantDigits = 4`

:`maximumSignificantDigits = 4`

, then `a`

will be formatted as "123.**5**",`b`

as "1.23**0**", and`c`

as "0.00123**0**"..*Note: The*.**4**→**5**conversions occur due to the round-to-nearest mode, as the digit following the 4 in a is 5.