NSNumberFormatter 和NSDateFormatter 是NsFormatter的子類。
NSNumberFormatter類有個屬性numberStyle，它是一個枚舉型，設(shè)置不同的值可以輸出不同的數(shù)字格式。該枚舉包括：

enum {
    NSNumberFormatterNoStyle = kCFNumberFormatterNoStyle, //無格式,四舍五入，原值2.7999999999,直接輸出3 
    NSNumberFormatterDecimalStyle = kCFNumberFormatterDecimalStyle, //小數(shù)型,保留小數(shù)輸出2.8
    NSNumberFormatterCurrencyStyle = kCFNumberFormatterCurrencyStyle, //貨幣型,加上了人民幣標(biāo)志，原值輸出￥2.8
    NSNumberFormatter
    NSNumberFormatterPercentStyle = kCFNumberFormatterPercentStyle,  //百分比型,本身數(shù)值乘以100后用百分號表示,輸出280%
    NSNumberFormatterScientificStyle = kCFNumberFormatterScientificStyle, //科學(xué)計數(shù)型,原值表示，輸出2.799999999E0
    NSNumberFormatterSpellOutStyle = kCFNumberFormatterSpellOutStyle  //全拼,原值的中文表示，輸出二點七九九九...
};

typedef NSUInteger NSNumberFormatterStyle;

各個枚舉對應(yīng)輸出數(shù)字格式的效果如下：

[1243:403] Formatted number string:123456789
[1243:403] Formatted number string:123,456,789
[1243:403] Formatted number string:￥123,456,789.00
[1243:403] Formatted number string:-539,222,988%
[1243:403] Formatted number string:1.23456789E8
[1243:403] Formatted number string:一億二千三百四十五萬六千七百八十九

其中第三項和最后一項的輸出會根據(jù)系統(tǒng)設(shè)置的語言區(qū)域的不同而不同

/**
 *  @author liboy
 *
 *  格式化余額數(shù)據(jù)
 *
 *  @param string 余額數(shù)據(jù)字符串
 *
 *  @return 帶逗號余額
 */
- (NSString *)balanceFormatFromStr:(NSString*)string
{
    NSNumberFormatter *numFormatter = [[NSNumberFormatter alloc] init];
    [numFormatter setNumberStyle:NSNumberFormatterCurrencyStyle];
    NSNumberFormatter *numFormatter2 = [[NSNumberFormatter alloc] init];
    [numFormatter2 setNumberStyle:NSNumberFormatterNoStyle];
    NSNumber *num = [numFormatter2 numberFromString:string];
    NSString *tempStr = [numFormatter stringFromNumber:num];
    NSString *balanceStr = [tempStr substringFromIndex:1];
    if ([tempStr hasPrefix:@"-"]) {
        balanceStr = [NSString stringWithFormat:@"-%@",[tempStr substringFromIndex:2]];
    }
    return balanceStr;
    
}