Xcode 将NSString转换为NSDecimalNumber

在我的核心数据模型中，数量是实体跟踪中的一个属性。如何在整个代码中将金额转换为NSDecimalNumber？我相信有经验的人可以在3分钟内完成这项工作，而我已经看了几天了

- (IBAction)save {
if (![amount.text isEqualToString:@""]) {
Tracking *tracking = [NSEntityDescription insertNewObjectForEntityForName:@"Tracking"
                                               inManagedObjectContext:self.managedObjectContext];

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *weightEntity = [NSEntityDescription entityForName:@"Tracking" inManagedObjectContext:self.managedObjectContext];
    [fetchRequest setEntity:weightEntity];
    NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"timestamp" ascending:NO];
    [fetchRequest setSortDescriptors:[NSArray arrayWithObject:sortDescriptor]];

    NSError *error = nil;
    NSArray *result = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];

    Tracking *person = [result objectAtIndex:0];

    NSLog(@"%@",person.date);

        NSDate *date = [NSDate date];
    NSDateFormatter *dateFormat = [[NSDateFormatter alloc]init];
    [dateFormat setDateFormat:@"MMM dd, yyyy"];

    NSString *dateString = [dateFormat stringFromDate:date];
    //NSString *dateString = @"Jan 13 2013";
    //Tracking *track = [self.fetchedResultsController objectAtIndexPath:nil];

tracking.note = note.text;
tracking.amount = amount.text;
tracking.title = [segmentedChoice titleForSegmentAtIndex:segmentedChoice.selectedSegmentIndex];
tracking.date = dateString;
tracking.timestamp = date;

        if (![person.date isEqualToString:dateString]) {

        if ([[segmentedChoice titleForSegmentAtIndex:segmentedChoice.selectedSegmentIndex] isEqualToString:@"Food/Drink"]) {
            tracking.pic = @"Drink";
            tracking.total = [NSString stringWithFormat:@"%.2f", 0.00 - [amount.text floatValue]];
            NSLog(@"%f",[person.total floatValue]);
            NSLog(@"%f", [amount.text floatValue]);
            //tracking.total = @"1000.00";
        }
        else if ([[segmentedChoice titleForSegmentAtIndex:segmentedChoice.selectedSegmentIndex] isEqualToString:@"Other"]) {
            tracking.total = [NSString stringWithFormat:@"%.2f",0.00 - [amount.text floatValue]];
            tracking.pic = [segmentedChoice titleForSegmentAtIndex:segmentedChoice.selectedSegmentIndex];

        }

        else {
            tracking.pic = [segmentedChoice titleForSegmentAtIndex:segmentedChoice.selectedSegmentIndex];
            tracking.total = [NSString stringWithFormat:@"%.2f",0.00 + [amount.text floatValue]];
        }

    }

    else {


        if ([[segmentedChoice titleForSegmentAtIndex:segmentedChoice.selectedSegmentIndex] isEqualToString:@"Food/Drink"]) {
            tracking.pic = @"Drink";
            tracking.total = [NSString stringWithFormat:@"%.2f",[person.total floatValue] - [amount.text floatValue]];
            NSLog(@"%f",[person.total floatValue]);
            NSLog(@"%f", [amount.text floatValue]);
    //tracking.total = @"1000.00";
            }
        else if ([[segmentedChoice titleForSegmentAtIndex:segmentedChoice.selectedSegmentIndex] isEqualToString:@"Other"]) {
            tracking.total = [NSString stringWithFormat:@"%.2f",[person.total floatValue] - [amount.text floatValue]];
            tracking.pic = [segmentedChoice titleForSegmentAtIndex:segmentedChoice.selectedSegmentIndex];

        }

        else {
            tracking.pic = [segmentedChoice titleForSegmentAtIndex:segmentedChoice.selectedSegmentIndex];
            tracking.total = [NSString stringWithFormat:@"%.2f",[person.total floatValue] + [amount.text floatValue]];

        }
    }

NSLog(@"\n Title: %@ \n Amount: %@ \n Note: %@ \n Date: %@ \n Picture: %@.png \n Total: %@ \n TimeStamp: %@", tracking.title, tracking.amount, tracking.note,tracking.date,tracking.pic, tracking.total, tracking.timestamp);

   [self.managedObjectContext save:nil];

   /* UIAlertView *alert = [[UIAlertView alloc] initWithTitle:[NSString stringWithFormat:@"%@ Saved",tracking.title] message:[NSString stringWithFormat:@"Amount: %@ \n Note: %@",tracking.amount,tracking.note] delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
    [alert show];*/

    [amount resignFirstResponder];
    [note resignFirstResponder];
    [self dismissViewControllerAnimated:YES completion:nil];
}

---

NSDecimalNumber具有以下方法，您可以使用这些方法将NSString转换为它：

+ (NSDecimalNumber *)decimalNumberWithString:(NSString *)numericString

例如：

NSString *foo = @"1.0";
NSDecimalNumber *cow = [NSDecimalNumber decimalNumberWithString:foo];

---

该类的完整参考可在此处找到：

NSDecimalNumber具有以下方法，您可以使用这些方法将NSString转换为它：

+ (NSDecimalNumber *)decimalNumberWithString:(NSString *)numericString

例如：

NSString *foo = @"1.0";
NSDecimalNumber *cow = [NSDecimalNumber decimalNumberWithString:foo];

课程的完整参考资料可在此处找到：

给你：

NSString *order; 
NSDecimalNumber *decimal = [NSDecimalNumber decimalNumberWithString:order];

给你：

NSString *order; 
NSDecimalNumber *decimal = [NSDecimalNumber decimalNumberWithString:order];

---

使用[cow doubleValue]获取原始值。使用[cow doubleValue]获取原始值。您好，我的字符串是@12.30，然后它返回12.3。它删除零我不想删除零。我该怎么做请帮助我。谢谢你，我尝试过这种方法，但它与修复分词一起工作，我想要动态的，所以我如何才能做到这一点。？还请检查此Hi我的字符串是@12.30，然后返回12.3它删除零我不想删除零我如何可以这样做，请帮助我。谢谢你，我尝试过这种方法，但它与修复分词一起工作，我想要动态的，所以我如何才能做到这一点。？也检查一下这个