IOS 取值控件(UIPicker)的使用方法

1.简单地取值控件示例

我们要做的一个UITextFiled,当点击UITextFiled，出现一个UIPick取值的页面，可以选择性别,在viewDidLoad中写下

//sexPicker
    UIPickerView *sexPicker=[[UIPickerView alloc]init];
    sexPicker.showsSelectionIndicator=YES;
    sexPicker.delegate=self;
    sexPicker.dataSource=self;
    self.sex.inputView=sexPicker;

对于数据源回调函数和代理回调函数的实现，代码如下:

 #pragma sexPicker
 -(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
 {
     return rSexComponentCount;
 }

 -(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
 {
     return rSexRowCount;
 }

 -(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
 {
     if(==row)
     {
         return @"Male";
     }
     else
     {
         return @"Female";
     }
 }

 -(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
 {
     if (==row) {
         self.sex.text=@"Male";
     }
     else
     {
         self.sex.text=@"FeMale";
     }
 }

显示结果如图：

2.UIPickData的使用

在viewDidLoad中添加如下代码：

//birthday Picker Choose
    self.birthdate.clearButtonMode=UITextFieldViewModeNever;
    UIDatePicker *birthPicker=[[UIDatePicker alloc]init];
    birthPicker.datePickerMode=UIDatePickerModeDate;
    //birthPicker.locale=[[NSLocale alloc]initWithLocaleIdentifier:<#(NSString *)#>];
    NSDateFormatter *formatter=[[NSDateFormatter alloc]init];
    formatter.dateFormat=@"MM-dd-yyyy";
    NSString *stdDate=@"01-01-1990";
    birthPicker.date=[formatter dateFromString:stdDate];
    [birthPicker addTarget:self action:@selector(chooseDate:) forControlEvents:UIControlEventValueChanged];
    self.birthdate.inputView=birthPicker;

其的触发事件函数

#pragma DatePicker
-(void)chooseDate:(UIDatePicker *)datePicker
{
    NSDate *date=datePicker.date;
    NSDateFormatter *formatter=[[NSDateFormatter alloc]init];
    formatter.dateFormat=@"MM-dd-yyyy";
    NSString *dateString=[formatter stringFromDate:date];
    self.birthdate.text=dateString;

    //[showAllBarButton appendString:[[NSString alloc] initWithString:dateString]];
    //self.barButtonItem.title=showAllBarButton;

}

运行结果:

3.自定义UIPicker的选项外观

除了通过简单的字符串进行UIPicker的显示之外，系统也提供了自定义视图的方法来为每一个选项进行自定义，API如下：

-(UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view

虽然在每次调用此方法时都重新生成一个全新的UIView子类对象，配置完后返回给调用者也能够达到自定义选项的效果。不过就像UITableView的重用机制般，这里也必须考虑到当选项数量特别巨大时，有理由使用此代理方法提供的reusingView参数来重用之前的视图。

所以为了方便维护和扩展起见，专门新建一个自定义的UIView子类比较好，取名为customRowView，考虑到需要让此类有一定的外部配置功能，所以customRowView的头文件可以设置如下:

 #import <UIKit/UIKit.h>

 #define CUSTOM_HEIGHT 60.0f
 #define CUSTOM_WIDTH 240.0f

 @interface HBCustomRowView : UIView
 {
     @private
     UIImageView *_photoView;
     UILabel *_nameLabel;
 }

 @property(nonatomic,retain) UIImage *photo;
 @property(nonatomic,retain) NSString *name;

 @end

上述代码中，两个属性photo和name是专供外部进行重用配置的，而长度的宏定义是为新建对象和实现特定UIPicker代理方法服务。

- (void)drawRect:(CGRect)rect
{
    // Drawing code
    //照片
    if (!_photoView) {
        _photoView = [[UIImageView alloc]initWithFrame:CGRectMake(10.0f, 0.0f, CGRectGetWidth(self.frame)-50.0f, CGRectGetHeight(self.frame))];

        _photoView.backgroundColor = [UIColor clearColor];
        [self addSubview:_photoView];
    }

    _photoView.image=self.photo;

    //球员名字
    if (!_nameLabel) {
        _nameLabel = [[UILabel alloc] initWithFrame:CGRectMake(CGRectGetMaxX(_photoView.frame), 0.0f, CGRectGetWidth(self.frame)-CGRectGetMaxX(_photoView.frame)-5.0f, CGRectGetHeight(self.frame))];
        _nameLabel.backgroundColor = [UIColor clearColor];
        _nameLabel.textAlignment = NSTextAlignmentRight;
        _nameLabel.textColor = [UIColor darkGrayColor];
        _nameLabel.shadowColor = [UIColor blackColor];
        _nameLabel.shadowOffset = CGSizeMake(1.0f, 1.0f);
        _nameLabel.numberOfLines=;
        _nameLabel.font = [UIFont systemFontOfSize:14.0f];

        [self addSubview:_nameLabel];
    }
    _nameLabel.text=self.name;
}

然后需要UIPickerView准备一个数据源对象和代理对象，此对象的相关代码实现如下:

#pragma mark-
#pragma mark UIPicker datasource
//几列
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    //只显示球员
    return ;
}

//每列多少行选项
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    return _datasource.count;
}

#pragma mark-
#pragma mark UIPicker delegate
//每列的宽度
-(CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component
{
    return 240.0f;
}

//每列的高
-(CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component
{
    return 60.0f;
}

//那列第几行的内容的标题
-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    return @"";
}

//选中任何列的某一行
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
}

//自定义UIPickerView的选项视图
-(UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view
{
    HBCustomRowView *aCustomView = nil;
    HBPlayerInfo *onePlayer =nil;

    //异常
    if(row>=_datasource.count)
    {
        return [[UIView alloc]init];
    }
    //取出相应的球员对象
    NSDictionary *player=[_datasource objectAtIndex:row];
    onePlayer.name=[player objectForKey:@"name"];
    onePlayer.role=[player objectForKey:@"role"];
    onePlayer.number=[player objectForKey:@"number"];
    if(view)
    {
        //重用
        aCustomView=(HBCustomRowView *)view;

        //让重用的视图再次调用drawRect方法
        [aCustomView setNeedsDisplay];
    }
    else
    {
        //新建
        aCustomView =[[HBCustomRowView alloc]initWithFrame:CGRectMake(0.0f, 0.0f, 240.0f, 60.0f)];
        aCustomView.backgroundColor=[UIColor clearColor];
    }

    //配置自定义视图
    aCustomView.photo = [UIImage imageNamed:@"gaolin.jpeg"];
    aCustomView.name=onePlayer.name;

    return  aCustomView;
}