ios - UILabel 中的 iOS 值中的 UIStepper

Question

您好，我正在 tableview 单元格中使用 UIStepper。当 UIStepper 值更改时，我必须在表格 View 单元格的标签中显示值。这是代码

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
       UILabel *lblQuantityValue = [[UILabel alloc] initWithFrame:CGRectMake(140, 410, 50, 30)];
       lblQuantityValue.text = @"1";
       lblQuantityValue.tag = indexPath.section;
       lblQuantityValue.backgroundColor = [UIColor clearColor];
       [[lblQuantityValue layer] setCornerRadius:5];
       [[lblQuantityValue layer] setMasksToBounds:YES];
       [[lblQuantityValue layer] setBorderWidth:1.0f];
       [[lblQuantityValue layer] setBorderColor:[[UIColor orangeColor]CGColor]];
       [cell addSubview:lblQuantityValue];

       UIStepper *stepper = [[UIStepper alloc] initWithFrame:CGRectMake(200, 410, 50, 30)];
       [stepper addTarget:self action:@selector(stepper_ValueChanged:) for   ControlEvents:UIControlEventValueChanged];
       stepper.tag = indexPath.row;
       stepper.minimumValue = 1;
       stepper.maximumValue = 10;
       [cell addSubview:stepper];
}

stepper_ValueChanged方法如下

-(void)stepper_ValueChanged:(UIStepper*)sender
{
 UILabel *lblQuantityValue = (UILabel*)[self.view viewWithTag:sender.tag];
 int value2 = [sender value];
 lblQuantityValue.text = [NSString stringWithFormat:@"%d", value2];
}

我收到如下崩溃报告

-[UIView setText:]: unrecognized selector sent to instance 0x111e10640
2014-02-26 11:22:24.159 Hyderabad Bazar[2115:a0b] *** Terminating app due to uncaught     exception 'NSInvalidArgumentException', reason: '-[UIView setText:]: unrecognized selector sent to instance 0x111e10640'
*** First throw call stack:
(
0   CoreFoundation                      0x0000000101ce3795 __exceptionPreprocess + 165
1   libobjc.A.dylib                     0x00000001019bf991 objc_exception_throw + 43
2   CoreFoundation                      0x0000000101d74bad -[NSObject(NSObject) doesNotRecognizeSelector:] + 205
3   CoreFoundation                      0x0000000101cd509d ___forwarding___ + 973
4   CoreFoundation                      0x0000000101cd4c48 _CF_forwarding_prep_0 + 120
5   Hyderabad Bazar                     0x00000001000202a6 -[CartViewController stepper_ValueChanged:] + 390
6   UIKit                               0x0000000100628a8a -[UIApplication sendAction:to:from:forEvent:] + 104
7   UIKit                               0x0000000100628a20 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 17
8   UIKit                               0x00000001006fc91c -[UIControl _sendActionsForEvents:withEvent:] + 203
9   UIKit                               0x0000000100a895d7 -[UIStepper _updateCount:] + 338
10  UIKit                               0x0000000100a89346 -[UIStepper endTrackingWithTouch:withEvent:] + 32
11  UIKit                               0x00000001006fbe52 -[UIControl touchesEnded:withEvent:] + 472
12  UIKit                               0x000000010092cc0d _UIGestureRecognizerUpdate + 5149
13  UIKit                               0x000000010065d2e5 -[UIWindow _sendGesturesForEvent:] + 928
14  UIKit                               0x000000010065dfa5 -[UIWindow sendEvent:] + 910
15  UIKit                               0x0000000100637962 -[UIApplication sendEvent:] + 211
16  UIKit                               0x000000010062579f _UIApplicationHandleEventQueue + 9549
17  CoreFoundation                      0x0000000101c72e61 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
18  CoreFoundation                      0x0000000101c72732 __CFRunLoopDoSources0 + 242
19  CoreFoundation                      0x0000000101c8e5bf __CFRunLoopRun + 767
20  CoreFoundation                      0x0000000101c8ded3 CFRunLoopRunSpecific + 467
21  GraphicsServices                    0x000000010408a3a4 GSEventRunModal + 161
22  UIKit                               0x0000000100627a63 UIApplicationMain + 1010
23  Hyderabad Bazar                     0x00000001000274e3 main + 115
24  libdyld.dylib                       0x00000001028067e1 start + 0

请帮帮我

Answer 1

您可能会发现两种不同的方法更可行:

子类 UITableViewCell，添加 UIStepper 和 UILabel 作为单元格的属性，并将单元格添加为 UISteppers valueChanged 操作的目标，在值更改时更新标签。根据您希望如何持久化事物，这可能会因出队和 prepareForReuse 而变得不稳定，这使我们想到了另一个想法...

或

创建一个适当的类变量或属性 NSMutableArray 来保存所有单元格的文本，无论它们是否可见。标签总是从这个数组中填充，而不是直接从步进器中填充。您仍然使用 Target/Action 对让单元格响应来自 UIStepper 的 valueChanged 事件，但是您将 tableView 连接为单元格的委托(delegate)，并使用协议(protocol)从单元格中进行这样的调用:

[self.tableViewDelegate newValue:value forCell:self];

然后让 tableView 像这样实现协议(protocol)方法:

- (void)newValue:(NSString*)value forCell:(CustomCellClassName*)cell
{
    NSIndexPath *indexPath = [self.tableView indexPathForCell:cell];
    //now use the index path to set the "value" parameter at the right place in your class variable or property

    //Now that the data source is updated, refresh the table
    [self.tableView reloadData];
}