iOS 阿拉伯数字转大写

以下是 iOS 中将阿拉伯数字转换为大写的示例代码：

- (NSString *)convertNumberToWords:(NSNumber *)number {
    static NSArray *onesPlace = nil;
    static NSArray *tensPlace = nil;
    static NSArray *thousandsPlace = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        onesPlace = @[@"", @"One", @"Two", @"Three", @"Four", @"Five", @"Six", @"Seven", @"Eight", @"Nine", @"Ten", @"Eleven", @"Twelve", @"Thirteen", @"Fourteen", @"Fifteen", @"Sixteen", @"Seventeen", @"Eighteen", @"Nineteen"];
        tensPlace = @[@"", @"", @"Twenty", @"Thirty", @"Forty", @"Fifty", @"Sixty", @"Seventy", @"Eighty", @"Ninety"];
        thousandsPlace = @[@"", @"Thousand", @"Million", @"Billion", @"Trillion", @"Quadrillion", @"Quintillion", @"Sextillion", @"Septillion", @"Octillion", @"Nonillion", @"Decillion"];
    });

    NSMutableString *result = [NSMutableString string];
    NSInteger remainingNumber = number.integerValue;

    if (remainingNumber == 0) {
        return @"Zero";
    }

    for (NSInteger i = thousandsPlace.count - 1; i >= 0; i--) {
        NSInteger divisor = pow(1000, i);
        NSInteger quotient = remainingNumber / divisor;
        remainingNumber %= divisor;

        if (quotient > 0) {
            NSString *thousandsString = [self convertNumberToWords:@(quotient)];
            NSString *thousandsPlaceString = thousandsPlace[i];
            [result appendFormat:@"%@ %@ ", thousandsString, thousandsPlaceString];
        }
    }

    if (remainingNumber >= 100) {
        NSInteger quotient = remainingNumber / 100;
        remainingNumber %= 100;
        NSString *hundredsString = onesPlace[quotient];
        NSString *hundredPlaceString = @"Hundred";
        [result appendFormat:@"%@ %@ ", hundredsString, hundredPlaceString];
    }

    if (remainingNumber >= 20) {
        NSInteger quotient = remainingNumber / 10;
        remainingNumber %= 10;
        NSString *tensString = tensPlace[quotient];
        [result appendString:tensString];
    }

    if (remainingNumber > 0) {
        NSString *onesString = onesPlace[remainingNumber];
        [result appendString:onesString];
    }

    return result;
}

使用示例：

NSNumber *number = @123456789;
NSString *words = [self convertNumberToWords:number];
NSLog(@"%@", words); // "One Hundred Twenty Three Million Four Hundred Fifty Six Thousand Seven Hundred Eighty Nine"

请注意，此代码仅支持处理到十的百万级别。如果需要处理更大的数字，请相应地增加 `thousandsPlace` 数组的元素。