基本的例子

迅速

class PickerViewExampleViewController : UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {
    @IBOutlet weak var btnFolder: UIButton!
    let pickerView = UIPickerView()
    let pickerViewRows = ["First row,", "Secound row,","Third row,","Fourth row"]
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.btnFolder.addTarget(self, action: #selector(CreateListVC.btnFolderPress), forControlEvents: UIControlEvents.TouchUpInside)
    }
    
    @objc private func btnFolderPress() {
        self.pickerView.delegate = self
        self.pickerView.dataSource = self
        self.view.addSubview(self.pickerView)
    }
    
    //MARK: UIPickerViewDelegate
    
    func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        return self.pickerViewRows[row]
    }
    
    //MARK: UIPickerViewDataSource
    
    func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
        return 1
    }
    
    func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        return self.pickerViewRows.count
    }
    
}

Objective-C

@property (nonatomic,strong) UIPickerView *countryPicker;
@property (nonatomic,strong) NSArray *countryNames;

- (void)viewDidLoad {
    [super viewDidLoad];
    _countryNames = @[@"Australia (AUD)", @"China (CNY)",
                          @"France (EUR)", @"Great Britain (GBP)", @"Japan (JPY)",@"INDIA (IN)",@"AUSTRALIA (AUS)",@"NEW YORK (NW)"];
    
   [self pickcountry];
 }

-(void)pickcountry {
    _countryPicker = [[UIPickerView alloc]init];
    
    _countryPicker.delegate = self;
    _countryPicker.dataSource = self;
    
    [[UIPickerView appearance] setBackgroundColor:[UIColor colorWithRed:21/255.0 green:17/255.0 blue:50/255.0 alpha:1.0]];
}

#pragma mark-  pickerView Delegates And datasource

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
    return 1;
}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
    return _countryNames.count;
}

- (NSString *)pickerView:(UIPickerView *)pickerView
             titleForRow:(NSInteger)row
            forComponent:(NSInteger)component {
    return _countryNames[row];
}

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
      NSString *pickedCountryName = _countryNames[row];
}