无数据源时获取UIPickerView选中值的最优方案

Hey there! Since you don't have a dedicated data source array to reference, the best way to get the selected values from your UIPickerView is to reuse the same mapping logic you already implemented in titleForRow. This ensures consistency between what's displayed and what you retrieve, plus it avoids redundant code.

Here's how to do it step by step:

1. Use the didSelectRow delegate method (for real-time selection updates) #

If you need to react immediately when the user selects a row, implement this delegate method. Inside it, you can calculate the selected value using your existing component/row logic:

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    let selectedValue: String
    if component == 0 {
        selectedValue = "\(row)."
    } else {
        selectedValue = "\(row)"
    }
    // Do something with selectedValue for this component, e.g. update a label or store it
    print("Selected value for component \(component): \(selectedValue)")
}

2. Create a helper method to fetch all selected values at once #

If you need to get all 3 components' values later (like when the user taps a "Confirm" button), make a reusable method that loops through each component, gets the selected row, and applies your mapping logic:

func fetchAllSelectedPickerValues() -> [String] {
    var selectedValues = [String]()
    let componentCount = pickerView.numberOfComponents
    
    for component in 0..<componentCount {
        let selectedRow = pickerView.selectedRow(inComponent: component)
        let value = component == 0 ? "\(selectedRow)." : "\(selectedRow)"
        selectedValues.append(value)
    }
    
    return selectedValues
}

Why this works so well: #

• Consistency: You're using the exact same logic that generates the picker's display text, so there's no chance of mismatch between what the user sees and what you retrieve.
• Low maintenance: If you ever need to change how values are formatted (e.g., add leading zeros to component 1), you only need to update the logic in one place (and keep titleForRow in sync, of course).
• No extra data storage: You don't need to maintain a separate array just to track values—you're deriving them directly from the row numbers, which is exactly what your picker uses to display content.

Just a quick tip: To keep your code DRY (Don't Repeat Yourself), you could even extract the mapping logic into a separate helper function that both titleForRow and your selection methods use. For example:

func valueForRow(_ row: Int, inComponent component: Int) -> String {
    return component == 0 ? "\(row)." : "\(row)"
}

// Then use it in titleForRow:
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    return valueForRow(row, inComponent: component)
}

// And in didSelectRow or fetchAllSelectedPickerValues:
let selectedValue = valueForRow(selectedRow, inComponent: component)

This way, you only have to update the formatting logic once if things change!

内容的提问来源于stack exchange，提问作者Artiom