objective-c - 如何以这种格式显示数字？

Question

我正在文本字段中显示一个数字。它将数字显示为“1234”，但如果我输入另一个显示为“12345”的大数字，我想将其显示为“1,234”的格式，但如果我输入 123456，我想将其显示为“12,345”显示为“123,456”。如何将此数字格式化为所需的格式？

-(void)clickDigit:(id)sender
{
    NSString * str = (NSString *)[sender currentTitle];
    NSLog(@"%@",currentVal);


    if([str isEqualToString:@"."]&& !([currentVal rangeOfString:@"."].location == NSNotFound) ) 
    {
        return;
    }
    if ([display.text isEqualToString:@"0"])
    {

        currentVal = str;
        [display setText:currentVal];
    }

    else if([currentVal isEqualToString:@"0"])
    {
        currentVal=str;
        [display setText:currentVal];

    }
    else
    {
        if ([display.text length] <= MAXLENGTH) 
        {
            currentVal = [currentVal stringByAppendingString:str];
            NSLog(@"%@",currentVal);
            [display setText:currentVal];
        }
        currentVal=display.text;
    }
}

这是我用来在文本字段中显示数字的代码。

---

编辑:我将代码更改为以下内容，但仍然没有得到正确格式的数字:

if ([display.text length] <= MAXLENGTH) {
    currentVal = [currentVal stringByAppendingString:str];
    NSNumberFormatter * myNumFormatter = [[NSNumberFormatter alloc] init];
    [myNumFormatter setNumberStyle:NSNumberFormatterDecimalStyle]; 
    NSNumber *tempNum = [myNumFormatter numberFromString:currentVal];
    NSLog(@"My number is %@",tempNum);
    [display setText:[tempNum stringValue]];
    currentVal=display.text;
}

Answer 1

你可以这样做:

int myInt = 12345;
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
formatter.numberStyle = NSNumberFormatterDecimalStyle;
NSNumber *number = [NSNumber numberWithInt:myInt];
NSLog(@"%@", [formatter stringFromNumber:number]); // 12,345

编辑

你没有正确实现这一点，关键是使用[formatter stringFromNumber:number]获取数字的字符串表示形式，但你没有这样做。因此，将您的代码更改为:

currentVal = [currentVal stringByAppendingString:str];
NSNumberFormatter * myNumFormatter = [[NSNumberFormatter alloc] init];
[myNumFormatter setNumberStyle:NSNumberFormatterDecimalStyle]; 
NSNumber *tempNum = [myNumFormatter numberFromString:currentVal];
NSLog(@"My number is %@",tempNum);
[display setText:[myNumFormatter stringFromNumber:tempNum]]; // Change this line
currentVal=display.text;
NSLog(@"My formatted number is %@", currentVal);