的iOS UiPickerView（-Helper）将发送消息

我所试图做的事：我有的iOS UiPickerView（-Helper）将发送消息

一个ViewController：

@implementation ViewController 
@synthesize myPicker; 
@synthesize myPickerHelper; 
@synthesize label; 

#pragma mark - View lifecycle 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    myPickerHelper = [[UIPickerViewHelper alloc]initWithUIPickerView:myPicker andNumberOfComponents:4]; 

    [myPickerHelper.valuesForComponent1 addObject:@"TEST1"]; 
    [myPickerHelper.valuesForComponent1 addObject:@"TEST2"]; 
    ; 

    [weightsPicker reloadAllComponents]; 
    [weightsPicker selectRow:0 inComponent:0 animated:YES]; 
    //TODO receive message from picker helper. 
    //label.text = ... set a listner (like that one in java) or what else 
    } 

}

而且我有一个PickerViewHelper：（它处理的委托和数据源的问题）

@interface UIPickerViewHelper : NSObject <UIPickerViewDelegate, UIPickerViewDataSource, OnPickerViewChangeDelegate> 

@implementation UIPickerViewHelper 
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component 
{ 
    //TODO send message to controller view. 
}

和协议：

@protocol OnPickerViewChangeDelegate 
@optional 
-(void)onChange:(NSString*)result; 
@end

我想要的是在我的UiPickerViewHelper类中使用协议方法“onChange”，以便我的标签（在我的ViewController中）将被通知。我知道如何解决在Java中，但我不知道如何解决在目标c。

问候

来源

2013-02-25 Steffen Ruppel

UIPickerViewHelper.h

@property (nonatomic, assign) id <OnPickerViewChangeDelegate> delegate

UIPickerViewHelper.m

@synthesize delegate; 

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component 
{ 
    //TODO send message to controller view. 
    [self.delegate onChange:[NSString stringWithFormat:@"Selected row %d", row]]; 
}

ViewController.m

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    myPickerHelper = [[UIPickerViewHelper alloc]initWithUIPickerView:myPicker andNumberOfComponents:4]; 
    myPickerHelper.delegate = self; 

    ... 
} 

-(void)onChange:(NSString*)result { 

    NSLog(@"Here is the result: %@", result); 
    label.text = result; 
}

来源

2013-02-25 14:26:59

OK !!!这样可行！但我不明白为什么...为什么视图控制器知道（或可以覆盖）onchange方法？ – 2013-02-25 15:11:38

由于视图控制器符合'OnPickerViewChangeDelegate'协议，这意味着视图控制器必须实现该方法。它不是压倒性的，它只是在实施它。 – 2013-02-25 15:16:52

@ user2075873请将我的答案标记为已接受（复选标记），如果它帮助您:) – 2013-02-25 15:35:02

没有UIPickerview委托方法进行更改。因为它会停在任意位置和

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component

方法将被调用，因此，如果用户退出选择器停止动画/轧制前... 隐藏的UIPickerView必须调用最后选定的值uipicker方法同时滚动/动画。

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component 
    { 
    if(delegate respondsToSelector:@selector(onChange:)){ 
     [delegate onChange:row];//return the index of row selected 
    } 
    }

来源

2013-02-25 14:36:27 yunas

的iOS UiPickerView（-Helper）将发送消息

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