UIPickerView 详解

<UIPickerViewDataSource,UIPickerViewDelegate> 实现这二个协议

UIPickerView *pv = [[UIPickerView alloc] init];
    pv.delegate = self;
    pv.dataSource = self;
    pv.showsSelectionIndicator = YES; // 是否显示选择标示

    -(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
        return 3;   // 3 列
    }
    -(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component{
        return 10;  // 每列10行
    }
    -(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{
        return [NSString stringWithFormat:@"%d-%d",row,component];  // 每条显示内容
    }
    -(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component{
        // 用户选择的内容
    }
    -(CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component{
        return 10; // 行高
    }
    -(CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component{
        return 10; // 行宽
    }