对金额字符串的处理3个数字一个逗号隔开

为了方便阅读，app中的金额需要用，隔开

//数字3个字一个逗号隔开，如：1,000.98
+ (NSString *)separatePer3WithNumStr:(NSString *)numStr{ 
    double oldf = [numStr doubleValue];
    long long oldll = [numStr longLongValue];
    YTLog(@"%@--%f---%lld",numStr,oldf,oldll);   
    double tmptf = oldf - oldll;   
    NSString *currencyStr = nil;   
    if(tmptf > 0){       
        currencyStr = [NSNumberFormatter localizedStringFromNumber:[NSNumber numberWithDouble:oldf]                    
                                                       numberStyle:NSNumberFormatterDecimalStyle];  
    }else{       
        currencyStr = [NSNumberFormatter localizedStringFromNumber:[NSNumber numberWithLongLong:oldll]                   
                                                       numberStyle:NSNumberFormatterDecimalStyle];       
    }   
    return currencyStr;   
}