如何在UIPickerView中设置默认的'top‘值？

// 在你的控制器或对象中
@interface YourViewController () <UIPickerViewDelegate, UIPickerViewDataSource>

@property (nonatomic, strong) UIPickerView *pickerView;
@property (nonatomic, strong) NSArray *data; // UIPickerView的数据源

@end

@implementation YourViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.pickerView = [[UIPickerView alloc] init];
    self.pickerView.delegate = self;
    self.pickerView.dataSource = self;
    
    // 设置默认的'top'值为第一行
    [self.pickerView selectRow:0 inComponent:0 animated:NO];
}

#pragma mark - UIPickerViewDataSource

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
    return 1; // 设置为1列
}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
    return self.data.count; // 返回数据源的数量
}

#pragma mark - UIPickerViewDelegate

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {
    return self.data[row]; // 返回每一行的标题
}

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
    // 在用户选择了某一行时，你可以在这里处理相应的逻辑
}

@end