UIPickerView的使用

UIPickerView功能与UIDatePicker类似

初始化实例时，通常只需要设置原点坐标，不需要设置宽高（默认宽高为：frame = (0 0; 320 216)）

区别在于:

1、UIPickerView需要自定义实现数据类型（包括：数据源，列数等）

@interface ViewController () <UIPickerViewDelegate, UIPickerViewDataSource>

@property (nonatomic, strong) NSDictionary *sourceDict;
@property (nonatomic, strong) NSString *rowTitleFirst;
@property (nonatomic, strong) NSString *rowTitleSecond;
@property (nonatomic, strong) NSString *rowTitleThird;

@property (nonatomic, strong) UITextField *textfield;

@end
           

UIPickerView *pickerView = [[UIPickerView alloc] init];
//    [self.view addSubview:pickerView];
pickerView.backgroundColor = [UIColor orangeColor];
NSLog(@"pickerView %@", pickerView);
           

/*
设置代理
1 包括代理对象，及数据源代理对象
2 实现代理方法的对象
3 添加协议
4 实现代理方法
     
注意事项
1、两种代理必须同时实现
2、标题显示设置三选一，只设置其中一个方法即可
2-1、- (nullable NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
2-2、- (nullable NSAttributedString *)pickerView:(UIPickerView *)pickerView attributedTitleForRow:(NSInteger)row forComponent:(NSInteger)component
2-3、- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(nullable UIView *)view
*/
pickerView.delegate = self;
pickerView.dataSource = self;
           

// 设置数据源
NSArray *meizhouArray = @[@"梅县", @"五华县", @"丰顺县", @"大埔县", @"蕉岭县", @"兴宁市", @"梅江区"];
NSArray *guangzhouArray = @[@"天河区", @"白云区", @"荔湾区", @"番禺区", @"海珠区", @"花都区", @"从化区", @"增城区"];
NSArray *shenzhenArray = @[@"龙华新区", @"大鹏新区", @"福田区", @"罗湖区", @"宝安区", @"龙岗区", @"南山区"];
NSDictionary *guangdongCityDict = [NSDictionary dictionaryWithObjectsAndKeys:shenzhenArray, @"深圳市", guangzhouArray, @"广州市", meizhouArray, @"梅州市", nil];
NSDictionary *guangxiCityDict = [NSDictionary dictionaryWithObjectsAndKeys:@[], @"柳州市", @[], @"桂林市", nil];
self.sourceDict = [NSDictionary dictionaryWithObjectsAndKeys:guangdongCityDict, @"广东省", guangxiCityDict, @"广西省", nil];
           

// 设置默认值
self.rowTitleFirst = @"广东省";
self.rowTitleSecond = @"深圳市";
[pickerView selectRow:0 inComponent:0 animated:NO];
[pickerView selectRow:0 inComponent:1 animated:NO];
[pickerView selectRow:3 inComponent:2 animated:NO];
           

// 刷新数据
[pickerView reloadAllComponents];
           

// 通过textfield来使用
self.textfield = [[UITextField alloc] initWithFrame:CGRectMake(10.0, 50.0, (CGRectGetWidth(self.view.bounds) - 10.0 * 2), 40.0)];
[self.view addSubview:self.textfield];
self.textfield.backgroundColor = [UIColor yellowColor];
self.textfield.textColor = [UIColor redColor];
self.textfield.placeholder = @"请选择地址（省市区）";
// 添加键盘上方的子视图
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
button.frame = CGRectMake(0.0, 0.0, CGRectGetWidth(self.view.bounds), 40.0);
button.backgroundColor = [UIColor greenColor];
[button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[button setTitleColor:[UIColor redColor] forState:UIControlStateHighlighted];
[button setTitle:@"隐藏键盘" forState:UIControlStateNormal];
[button addTarget:self action:@selector(hiddenKeyboard:) forControlEvents:UIControlEventTouchUpInside];
self.textfield.inputAccessoryView = button;
//输入源改成地址选择视图
self.textfield.inputView = pickerView;
           

// UIPickerViewDelegate

- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component
{
    // 设置列的宽度
    return 100.0;
}

- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component
{
    // 设置列中的每行的高度
    return 40.0;
}

- (nullable NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    // 设置列中的每行的显示标题NSString
    
    // 设置每列每行的标题
    NSArray *keyArray = self.sourceDict.allKeys;
    if (0 == component)
    {
        NSString *title = keyArray[row];
        return title;
    }
    else if (1 ==component)
    {
        NSDictionary *cityDict = self.sourceDict[self.rowTitleFirst];
        NSArray *cityArray = cityDict.allKeys;
        NSString *title = cityArray[row];
        return title;
    }
    else if (2 == component)
    {
        NSDictionary *areaDict = self.sourceDict[self.rowTitleFirst];
        NSArray *areaArray = areaDict[self.rowTitleSecond];
        NSString *title = areaArray[row];
        return title;
    }
    
    return nil;
}

//- (nullable NSAttributedString *)pickerView:(UIPickerView *)pickerView attributedTitleForRow:(NSInteger)row forComponent:(NSInteger)component
//{
//    // 设置列中的每行的显示标题NSAttributedString
//    return nil;
//}

- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(nullable UIView *)view
{
    // 设置列中的每行的自定义视图
    UILabel *label = (UILabel *)view;
    if (label == nil) {
        label = [[UILabel alloc] init];
        label.textColor = UIColor.blackColor;
        label.font = [UIFont systemFontOfSize:16.0];
        label.textAlignment = NSTextAlignmentCenter;
    }
    
    label.font = [UIFont systemFontOfSize:16.0];
    // 获取当前显示字符
    NSString *text = [self pickerView:pickerView titleForRow:row forComponent:component];
    // 当前列，需要在方法- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component中调用[pickerView reloadComponent:component];否则不会体现效果
    if (1 == component) {
        // 当前行是否为选中行
        if (self.selectedRow == row) {
            label.font = [UIFont systemFontOfSize:18.0];
            text = [text stringByAppendingString:@" 时"];
        }
    } else if (2 == component) {
        if (self.selectedComponent == row) {
            label.font = [UIFont systemFontOfSize:18.0];
            text = [text stringByAppendingString:@" 分"];
        }
    }
    label.text = text;
    
    return label;
}

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    // 获取列中选中的某一行
    
    NSLog(@"component = %ld, row = %ld", component, row);
    
    NSArray *keyArray = self.sourceDict.allKeys;
    if (0 == component)
    {
        NSString *keyFirst = keyArray[row];
        // 设置第一列的值，即key1
        self.rowTitleFirst = keyFirst;
        // 当第一列改变时，第二列的值应该跟着改变，即key2，设置为默认第二列的第一个值
        NSDictionary *cityDict = self.sourceDict[self.rowTitleFirst];
        NSArray *cityArray = cityDict.allKeys;
        if (cityArray && 0 < cityArray.count)
        {
            NSString *keySecond = cityArray[0];
            self.rowTitleSecond = keySecond;
        }
        // 设置第三个标题，当第二列改变时，第三wfhr值路着改变
        NSArray *areaArray = cityDict[self.rowTitleSecond];
        if (areaArray && 0 < areaArray.count)
        {
            NSString *keyThird = areaArray[0];
            self.rowTitleThird = keyThird;
        }
        else
        {
            // 没有第三列时，将第三列的默认标题设置为空
            self.rowTitleThird = nil;
        }
        
        // 重新刷新第2列的数据，且设置显示为第一行
        [pickerView reloadComponent:1];
        [pickerView selectRow:0 inComponent:1 animated:YES];
        
        // 重新刷新第3列的数据，且设置显示为第一行
        [pickerView reloadComponent:2];
        [pickerView selectRow:0 inComponent:2 animated:YES];
    }
    else if (1 ==component)
    {
        // 设置第二个标题
        NSDictionary *cityDict = self.sourceDict[self.rowTitleFirst];
        NSArray *cityArray = cityDict.allKeys;
        NSString *keySecond = cityArray[row];
        self.rowTitleSecond = keySecond;
        
        // 设置第三个标题，默认第一行
        NSArray *areaArray = cityDict[self.rowTitleSecond];
        if (areaArray && 0 < areaArray.count)
        {
            NSString *keyThird = areaArray[0];
            self.rowTitleThird = keyThird;
        }
        
        
        // 重新刷新第3列的数据，且设置显示为第一行
        [pickerView reloadComponent:2];
        [pickerView selectRow:0 inComponent:2 animated:YES];
    }
    else if (2 == component)
    {
        // 设置第三个标题
        NSDictionary *cityDict = self.sourceDict[self.rowTitleFirst];
        NSArray *areaArray = cityDict[self.rowTitleSecond];
        if (areaArray && 0 < areaArray.count)
        {
            NSString *keyThird = areaArray[row];
            self.rowTitleThird = keyThird;
        }
    }
    
    NSString *text = [NSString stringWithFormat:@"%@%@%@", self.rowTitleFirst, self.rowTitleSecond, self.rowTitleThird];
    NSLog(@"选择结果：%@", text);
    
    self.textfield.text = text;

    // 重置当前列的选中行
    if (1 == component) {
        self.selectedRow = row;
    } else if (2 == component) {
        self.selectedComponent = row;
    }
    // 刷新对应列，否则不会执行方法- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(nullable UIView *)view
    [pickerView reloadComponent:component];
}
           

// UIPickerViewDataSource

// returns the number of 'columns' to display.
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    // 设置列数
    
    // 设置三列：省、市、区
    return 3;
}

// returns the # of rows in each component..
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    // 设置每列的行数
    
    // 设置每列的实际行数
    NSArray *keyArray = self.sourceDict.allKeys;
    if (0 == component)
    {
        return keyArray.count;
    }
    else if (1 ==component)
    {
        NSDictionary *cityDict = self.sourceDict[self.rowTitleFirst];
        NSArray *cityArray = cityDict.allKeys;
        return cityArray.count;
    }
    else if (2 == component)
    {
        NSDictionary *areaDict = self.sourceDict[self.rowTitleFirst];
        NSArray *areaArray = areaDict[self.rowTitleSecond];
        return areaArray.count;
    }
    
    return 0;
}
           

// 隐藏键盘
- (void)hiddenKeyboard:(UIButton *)button
{
    [self.view endEditing:YES];
}