UIPickerView的使用

一般在应用程序中可能遇到像城市选择风格的UI ，那这个就是用UIPickerView来实现的 ；

UIPickerView的使用跟UITableView的使用很类似，都需要实现delegat 和dataSource。 那接下来看一下具体的操作步骤：

1.初始化pickerView 

         UIPickerView  *pickerView = [[UIPickerViewalloc]initWithFrame:CGRectMake(0,100,380,216)];

    pickerView.showsSelectionIndicator =YES;

    pickerView.delegate =self;

    pickerView.dataSource =self;

   // pickerView.backgroundColor = [UIColor redColor];

    [self.viewaddSubview:pickerView];

   

    NSString *path = [[NSBundlemainBundle] pathForResource:@"ProvincesAndCities"ofType:@"plist"];//此处的plist见附件

     provinceArr = [NSArrayarrayWithContentsOfFile:path];

     cityArr = [provinceArr[0]objectForKey:@"Cities"];

2.接下来实现代理和数据源方法  

//列数

-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView

{

   return 2;

    

}

//行数

-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component

{

    if(component==0)

     {

        return provinceArr.count;

     }

   return cityArr.count;

}

//每列高度

-(CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component

{

   return 60;

}

//每列宽度

-(CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component

{

    if(component==1)

     {

        return 200;

     }

   return 200;

}

//选中某一行

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

{

   

     if(component == 0)

      {

         cityArr = [[provinceArrobjectAtIndex:row] objectForKey:@"Cities"];

          [pickerViewselectRow:0inComponent:1animated:YES];

          [pickerViewreloadComponent:1];

      }

}

//返回每列当前行的内容

-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component

{

  if(component == 0)

   {

       return  [[provinceArrobjectAtIndex:row] objectForKey:@"State"];

   }

   else

    {

        return  [[cityArrobjectAtIndex:row] objectForKey:@"city"];

    }

    

}

3.此处还可以自定义每一列显示的样式   

  

//自定义

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

{

    if (view==nil)

    {

        view = [[UIViewalloc]init];

    }

    

    if(component == 0)

    {

        UILabel *la = [[UILabel alloc]initWithFrame:CGRectMake(10,20, 30, 30)];

        la.textAlignment =NSTextAlignmentCenter;

        la.text = [NSStringstringWithFormat:@"%ld",row];

        [view addSubview:la];

        

        UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(50,0, 120, 60)];

        label.backgroundColor = [UIColorredColor];

        label.text = [[provinceArrobjectAtIndex:row] objectForKey:@"State"];

        label.textAlignment =NSTextAlignmentCenter;

        [view addSubview:label];

        return view;

    }

    

    UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(10,0, 70, 60)];

    label.text = [[cityArrobjectAtIndex:row] objectForKey:@"city"];

    label.backgroundColor = [UIColorgreenColor];

    label.textAlignment =NSTextAlignmentCenter;

    [view addSubview:label];

    return view;

}

4.还可以设置字体  

   

-(NSAttributedString *)pickerView:(UIPickerView *)pickerView attributedTitleForRow:(NSInteger)row forComponent:(NSInteger)component

{

     NSString *str = nil ;

    if(component == 0)

    {

      str = [[provinceArrobjectAtIndex:row] objectForKey:@"State"];

    }

    else

    {

       str = [[cityArrobjectAtIndex:row] objectForKey:@"city"];

    }

    

    NSMutableAttributedString *attributeString = [[NSMutableAttributedStringalloc]initWithString:str];

    [attributeString addAttributes:@{NSFontAttributeName:[UIFontboldSystemFontOfSize:10.0f],NSForegroundColorAttributeName:[UIColorredColor]}range:NSMakeRange(0, [attributeStringlength])];

    

    return attributeString;

}