0

在我的应用程序中， s 列表中显示了许多UISwitches 和s。UITextFieldUITableViewCell

当用户开始编辑 aUITextField然后点击 aUISwitch时，事件的顺序会导致UITextField显示 的值，UISwitch因为事件处理程序没有收到 的结束编辑事件UITextField。

如何可靠地确保事件在UIControlEventEditingDidEnd事件之前UITextField被触发？UIControlEventValueChangedUISwitch

它会导致这样的错误（文本字段中显示的开关值）：

UISwitch 和 UITextField

步骤（应该发生什么）：

1.点击UISwitch激活它

UISwitch:startEditing:switch243
UISwitch:valueChanged:{true}
UISwitch:endEditing
UIEventHandler:saveValue:switch243:{true}

2.点击UITextField开始编辑

UITextField:startEditing:textfield455

3.点击UISwitch取消激活它

UITextField:endEditing
UISwitch:startEditing:switch243
UISwitch:valueChanged:{false}
UISwitch:endEditing
UIEventHandler:saveValue:switch243:{false}

控制台日志（实际发生的情况 - UISwitch 事件在 UITextField:endEditing 之前触发）：

UISwitch:startEditing:switch243
UISwitch:valueChanged:{true}
UISwitch:endEditing
UIEventHandler:saveValue:switch243:{true}
UITextField:startEditing:textfield455
UISwitch:startEditing:switch243
UISwitch:valueChanged:{false}
UISwitch:endEditing
UIEventHandler:saveValue:switch243:{false}
UITextField:endEditing

执行：

UITableViewCellWithSwitch.h：

@interface UITableViewCellWithSwitch : UITableViewCell
@property (nonatomic, strong) NSString *attributeID;
@property (nonatomic, retain) IBOutlet UISwitch *switchField;
@end

UITableViewCellWithSwitch.m：

@implementation UITableViewCellWithSwitch
- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier {
    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) {
        [self.switchField addTarget:self
                            action:@selector(switchChanged:)
                  forControlEvents:UIControlEventValueChanged];
    }
    return self;
}
// UIControlEventValueChanged
- (void)switchChanged:(UISwitch *)sender {
    NSLog(@"UISwitch:startEditing:%@",self.attributeID);
    [self handleStartEditingForAttributeID:self.attributeID];

    NSString* newValue = sender.on==YES?@"true":@"false";
    NSLog(@"UISwitch:valueChanged:{%@}", newValue);
    [self handleValueChangeForEditedAttribute:newValue];

    NSLog(@"UISwitch:endEditing");
    [self handleEndEditingForEditedAttribute];
}
@end

UITableViewCellWithTextField.h：

@interface UITableViewCellWithTextField : UITableViewCell<UITextFieldDelegate>
@property (nonatomic, strong) NSString *attributeID;
@property (strong, nonatomic) IBOutlet UITextField *inputField;
@end

UITableViewCellWithTextField.m：

@implementation UITableViewCellWithTextField
- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier {
    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) {
        [self.inputField addTarget:self
                            action:@selector(textFieldDidBegin:)
                  forControlEvents:UIControlEventEditingDidBegin];

        [self.inputField addTarget:self
                            action:@selector(textFieldDidChange:)
                  forControlEvents:UIControlEventEditingChanged];

        [self.inputField addTarget:self
                            action:@selector(textFieldDidEnd:)
                  forControlEvents:UIControlEventEditingDidEnd];
    }
    return self;
}
// UIControlEventEditingDidBegin
-(void) textFieldDidBegin:(UITextField *)sender {
    NSLog(@"UITextField:startEditing:%@",self.attributeID);
    [self handleStartEditingForAttributeID:self.attributeID];
}
// UIControlEventEditingChanged
-(void) textFieldDidChange:(UITextField *)sender {
    NSLog(@"UITextField:valueChanged:{%@}", sender.text);
    [self handleValueChangeForEditedAttribute:sender.text];
}
// UIControlEventEditingDidEnd
-(void) textFieldDidEnd:(UITextField *)sender {
    NSLog(@"UITextField:endEditing");
    [self handleEndEditingForEditedAttribute];
}
@end

UIEventHandler.m聚合所有 UI 编辑事件：

-(void) handleStartEditingForAttributeID:(NSString *)attributeID { 
    // Possible solution   
    //if (self.editedAttributeID != nil && [attributeID isEqualToString:self.editedAttributeID]==NO) { // Workaround needed for UISwitch events
    //    [self handleEndEditingForActiveAttribute];
    //}
    self.editedAttributeID = attributeID;
    self.temporaryValue = nil;
}

-(void) handleValueChangeForEditedAttribute:(NSString *)newValue {
    self.temporaryValue = newValue;
}

-(void) handleEndEditingForEditedAttribute { 
    if (self.temporaryValue != nil) { // Only if value has changed
        NSLog(@"UIEventHandler:saveValue:%@:{%@}", self.editedAttributeID, self.temporaryValue);

        // Causes the view to regenerate
        // The UITextField loses first responder status and UIControlEventEditingDidEnd is gets triggered too late
        [self.storage saveValue:self.temporaryValue 
                   forAttribute:self.editedAttributeID];

        self.temporaryValue = nil;
    }
    self.editedAttributeID = nil;
}
4

2 回答 2

1

如果我理解正确，您遇到的问题是当文本字段是第一响应者时更改开关值，然后您的文本字段的文本会更新为开关的值。

AUITextField的didEndEditing:事件仅在文本字段退出第一响应者时发生。如果您要做的只是确保在开关值更改时文本字段结束编辑，您应该endEditing:在开关收到UIControlEventValueChanged事件时将消息发送到活动文本字段。

现在，如何调用endEditing:文本字段上的消息取决于类的结构。您可以在表格视图单元格类上有一个指定的初始化方法，您可以在其中传递一个UITextField对应于UISwitch控制文本字段的实例。保持对文本字段实例的弱引用，然后endEditing:在开关值更改时调用。或者您可以简单地尝试调用[self endEditing:YES];whenUITableViewCellWithSwitch事件switchChanged:被触发或[self.superview endEditing:YES];. 我更喜欢前一种解决方案而不是后者，因为后者更像是一种破解而不是适当的解决方案。

更新：

查看您的代码后，您在问题中提到的错误的原因

它会导致这样的错误（文本字段中显示的开关值）：

是以下一段代码：

- (void)switchChanged:(UISwitch *)sender {
    NSLog(@"UISwitch:startEditing:%@",self.attributeID);
    [self handleStartEditingForAttributeID:self.attributeID];

    NSString* newValue = sender.on==YES?@"true":@"false";
    NSLog(@"UISwitch:valueChanged:{%@}", newValue);
    [self handleValueChangeForEditedAttribute:newValue];

    NSLog(@"UISwitch:endEditing");
    [self handleEndEditingForEditedAttribute];
}

您正在调用该handleValueChangeForEditedAttribute:属性的开关值，该属性实际上只应该保存文本字段的值。在您的UIEventHandler课程中，您正在使用方法中的开关值更新您的数据访问对象 (DAO) handleEndEditingForEditedAttribute。switchChanged:将您的方法的逻辑更改为如下所示：

- (void)switchChanged:(UISwitch *)sender {
    if (sender.on == YES) {
        [self handleStartEditingForAttributeID:self.attributeID];
    } else {
        [self handleEndEditingForEditedAttribute];
    }
}

在您的UIEventHandler课堂上，取消注释您帖子中“可能的解决方案”的评论行。这应该确保在存储新的值之前保存任何以前的更改attributeID。

-(void) handleStartEditingForAttributeID:(NSString *)attributeID { 
    // Possible solution   
    if (self.editedAttributeID != nil && [attributeID isEqualToString:self.editedAttributeID]==NO) { // Workaround needed for UISwitch events
        [self handleEndEditingForActiveAttribute];
    }
    self.editedAttributeID = attributeID;
    self.temporaryValue = nil;
}
于 2018-11-20T16:51:09.607 回答
0

我最好的解决方案是解决UIEventHandler.m. 如果在调用事件时尚未触发它，它会startEditing从.endEditingUIEventHandler

-(void) handleStartEditingForAttributeID:(NSString *)attributeID { 
    // Possible solution   
    if (self.editedAttributeID != nil && [attributeID isEqualToString:self.editedAttributeID]==NO) { // Workaround needed for UISwitch events
        [self handleEndEditingForActiveAttribute];
    }
    self.editedAttributeID = attributeID;
    self.temporaryValue = nil;
}

-(void) handleValueChangeForEditedAttribute:(NSString *)newValue {
    self.temporaryValue = newValue;
}

-(void) handleEndEditingForEditedAttribute { 
    if (self.temporaryValue != nil) { // Only if value has changed
        NSLog(@"UIEventHandler:saveValue:%@:{%@}", self.editedAttributeID, self.temporaryValue);

        // Causes the view to regenerate
        // The UITextField loses first responder status and UIControlEventEditingDidEnd is gets triggered too late
        [self.storage saveValue:self.temporaryValue 
                   forAttribute:self.editedAttributeID];

        self.temporaryValue = nil;
    }
    self.editedAttributeID = nil;
}
于 2018-11-22T08:30:44.210 回答