UIPickerView 设置showsSelectionInd

答案来源https://stackoverflow.com/questions/9069658/uipicker-view-selection-indicator-issue

正常生成pickerView：

UIPickerView *pickerView = [[UIPickerView alloc] initWithFrame:frame];

    pickerView.delegate=self;

    pickerView.dataSource=self;

    pickerView.showsSelectionIndicator = YES;

    [self.view addSubview:pickerView];

可能还会出现没有正常显示选择分割线的问题，解决办法是再加一行代码：

[pickerView selectRow:0 inComponent:0 animated:NO];

也就是手动设置一下默认选中行就可以了