Question

我正在开发一款包含收银机的iOS应用程序。我需要能够输入数字并使小数点保持原样就像真正的收银机一样。

目前使用的代码示例是：

-(IBAction)Number1:(id)sender{
    SelectNumber = SelectNumber * 10;
    SelectNumber = SelectNumber + 1;
    Screen.text = [NSString stringWithFormat:@"%i", SelectNumber];
}

例如，您可以从：

开始

0.00

然后按1

0.01

然后按2然后按3

1.23

然后是五个

12.35

目前，如果我这样做，我最终将从0.00变为1235（无小数）

我不知道怎么做到这一点，我的谷歌搜索迄今为止都没有让我失望。任何想法/解决方案？

Answer 1

您可以创建以所需格式显示数字的方法：

-(NSMutableString*)displayNumber:(NSString*)str {

    NSMutableString *myNumber = [NSMutableString stringWithFormat:@"%03d", [str intValue]];
    [myNumber insertString:@"." atIndex:myNumber.length-2];
    return myNumber;
}

您可以创建可变字符串来表示数字，只需附加另一个数字并使用displayNumber方法以您想要的格式显示它：

NSMutableString *number = [NSMutableString stringWithString:@""];
NSLog(@"%@", [self displayNumber:number]); // 0.00
[number appendString:@"2"];
NSLog(@"%@", [self displayNumber:number]); //0.02
[number appendString:@"3"];
NSLog(@"%@", [self displayNumber:number]); //0.23
[number appendString:@"1"];
NSLog(@"%@", [self displayNumber:number]); //23.1
[number appendString:@"5"];
NSLog(@"%@", [self displayNumber:number]); //23.15

您应该处理一些验证，以确保用户只添加数值。

Answer 2

您可以使用NSDecimalNumber。以下是基本要素：

用于保存用户输入的数字的可变字符串
保留实际号码的NSDecimalNumber
要在UI中显示该号码的NSNumberFormatter

// Our properties
@property (nonatomic, strong) NSNumberFormatter *numberFormatter;
@property (nonatomic, strong) NSDecimalNumber *accumulator;
@property (nonatomic, strong) NSMutableString *accumulatorString;

// Initial values
_accumulator = [NSDecimalNumber zero];
_accumulatorString = [NSMutableString stringWithString:@"0"];
_numberFormatter = [[NSNumberFormatter alloc] init];
_numberFormatter.numberStyle = NSNumberFormatterCurrencyStyle;
_numberFormatter.currencySymbol = @"$"; 
// You might want to adjust the formatter depending on the locale
// Here is a minimal setup just for the purpose of this example

// The user taps a number
// Of course the digit will be provided dynamically
// (something like [sender currentTitle] for example
// would be ok for a numeric keypad scenario)
[self.accumulatorString appendString:@"6"]; 

// Update our decimal number
// Here if our string is '06' with mantissa -2 => 0.06
// string '061' with mantissa -2 => 0.61 and so on...
self.accumulator = [NSDecimalNumber decimalNumberWithMantissa:[self.accumulatorString integerValue]
                                                     exponent:-2
                                                   isNegative:NO];

// Update the display
self.myDisplayLabel.text = [self.numberFormatter stringFromNumber:self.accumulator];

Objective-C收银机文本

2 个答案: