OC中小數(shù)的精確計(jì)算http://www.tuicool.com/articles/QzMFZf
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
formatter.numberStyle = kCFNumberFormatterDecimalStyle;
NSString *string = [formatter stringFromNumber:@123456789.89];
NSLog(@"%@",string);
kCFNumberFormatterDecimalStyle
123,456,789.89
kCFNumberFormatterCurrencyStyle
￥ 123,456,789.89
kCFNumberFormatterPercentStyle
12,345,678,989%
kCFNumberFormatterScientificStyle
1.2345678989E8
kCFNumberFormatterSpellOutStyle
一億二千三百四十五萬六千七百八十九點(diǎn)八九
kCFNumberFormatterOrdinalStyle
第1,2345,6790
輸出005
NSNumberFormatter *numberFormatter = [[NSNumberFormatter alloc] init];
NSInteger classCode = 5;
numberFormatter.numberStyle = kCFNumberFormatterNoStyle;
numberFormatter.formatWidth = 3; // 數(shù)據(jù)寬度為3，不足前面補(bǔ)0
numberFormatter.paddingCharacter = @"0";
NSString * schoolStuCode = [NSString stringWithFormat:@"%@", [numberFormatter stringFromNumber:@(classCode)]];
NSLog(@"schoolStuCode = %@", schoolStuCode); // 005
輸出005
NSInteger classCode = 5;
NSString *schoolStuCode = [NSString stringWithFormat:@"%3.3d", classCode];
NSLog(@"schoolStuCode = %@", schoolStuCode); // 005
聊聊NSNumber挤渔， NSNumber可以封裝c中基本數(shù)據(jù)類型 char屁奏，int看疙，long瘸爽，float，BOOL墓律，NSInteger钧嘶，CGFloat等。
NSNumber *num = [NSNumber numberWithChar:'a'];
NSLog(@"%@", num); // 97
num = [NSNumber numberWithInteger:97];
num = [NSNumber numberWithFloat:97.0];
num = [NSNumber numberWithBool:YES];
// 不過直接用下面的方式封裝會更方便
num = @'a';
num = @97;
num = @97.0;
num = @YES;
