UIPickerView

extension UIPickerView

Delegate and DataSource

UIPickerView closures make it easy to implement UIPickerViewDelegate and UIPickerViewDataSource protocol methods in an organized way. The following is an example of a simple collection view that displays strings in each row.

func loadPickerView() {
    pickerView
        .numberOfRowsInComponent() { _ in
            countries.count
        }.titleForRow() { row, component in
            countries[row]
        }.didSelectRow { row, component in
            log("\(countries[row]) selected")
        }.reloadAllComponents()
}

Arrays

These operations are common. Usually, they involve populating the UIPickerView with the values from an array. Closures framework gives you a convenient way to pass your collection to the table view, so that it can perform the boilerplate operations for you, especially the ones that are required to make the picker view perform at a basic level.

Important

Please remember that Swift Arrays are value types. This means that they are copied when mutaded. When the values or sequence of your array changes, you will need to call one of the add methods again, just before you call reloadData().

func loadPickerView(countries: [String]) {
    let reversed = Array(countries.reversed())
    pickerView
        .addStrings(reversed) { country,component,row in
            log("\(country) selected from array")
        }.reloadAllComponents()
}

Note

Be sure to note that most of the closure callbacks in these array binding methods switch the order of the parameters of row and component. Most of the UIPickerView delegate/datasource method parameters pass row,component. The parameters on the add methods switch the order and send component,row

Multiple Components

And finally, you can just as easily show mutliple components by binding a 2-dimensional array. When using this method, the outer dimension of the array is the component (columns) and the inner dimension are the rows in that component.

let anElement = myTwoDArray[component][row]

In this example, the more verbose row handler is provided just to show the different variations. Adding multiple components has a convenient method to deal with string only arrays also.

func loadPickerView(components: [[String]]) {
    pickerView.addComponents(
        components,
        rowTitle: { country,component,row in
            country},
        didSelect: { country,component,row in
            log("\(country) selected from 2D Array")
    })

    /**
     This also allows you to override any default behavior so
     you aren't overly committed, even though you're initially binding everything
     to the `Array`.
     */
    pickerView.widthForComponent { component in
        component ==  0 ? 200 : 100
    }.reloadAllComponents()
}

Common Array Usage


                    
                    
                    addStrings(_:didSelect:)

This method defaults many of the boilerplate callbacks needed to populate a UIPickerView when using an Array as a data source. The defaults that this method takes care of:

Provides the number of components
Provides the number of rows
Handles the pickerView(_:didSelectRow:inComponent:) delegate method
Provides the title string for each row

This method simply sets basic default behavior. This means that you can override the default picker view handlers after this method is called. However, remember that order matters. If you call this method after you override the numberOfComponents callback, for instance, the closure you passed into numberOfComponents will be wiped out by this method and you will have to override that closure handler again.

Important

Please remember that Swift Arrays are value types. This means that they are copied when mutaded. When the values or sequence of your array changes, you will need to call this method again, just before you call reloadComponent() or reloadAllComponents(). If you have a lot of picker view customization in addtion to a lot of updates to your array, it is more appropriate to use the individual closure handlers instead of this method.

An example of calling this method:

pickerView.addStrings(<#myArray#>) { aTitle,component,row in
    print("\(aTitle) was selected")
}

Declaration

Swift

@discardableResult
public func addStrings(_ strings: [String],
                       didSelect: @escaping (_ element: String, _ component: Int, _ row: Int) -> Void) -> Self

Parameters

`strings`	An `Array` of `String`s to be used for each row in a single component picker view.
`didSelect`	A closure that is called when the UIPickerView’s value has been selected.

Return Value

itself so you can daisy chain the other delegate/datasource calls


                    
                    
                    addElements(_:rowTitle:didSelect:)

This method defaults many of the boilerplate callbacks needed to populate a UIPickerView when using an Array as a data source. The defaults that this method takes care of:

Provides the number of components
Provides the number of rows
Handles the pickerView(_:titleForRow:forComponent:) delegate method
Handles the pickerView(_:didSelectRow:inComponent:) delegate method

Important

Be sure to note that most of the closure callbacks in these array binding methods switch the order of the parameters of row and component. Most of the UIPickerView delegate/datasource method parameters have row,component. The handlers’ parameters on the add methods send component,row.

An example of calling this method:

pickerView.addElements(
    <#myArray#>,
    rowTitle: { element, component, row in
        return <#aTitle(from: element)#>},
    didSelect: { element, component, row in
        print("\(element) was selected")
)

Declaration

Swift

@discardableResult
public func addElements<Element>(_ elements: [Element],
                                 rowTitle: @escaping (_ element: Element, _ component: Int, _ row: Int) -> String,
                                 didSelect: @escaping (_ element: Element, _ component: Int, _ row: Int) -> Void) -> Self

Parameters

`strings`	An `Array` of any type to be used for each row in a single component picker view.
`rowTitle`	A closure that is called when the UIPickerView needs to display a string for it’s row.
`didSelect`	A closure that is called when the UIPickerView’s value has been selected.

Return Value

itself so you can daisy chain the other delegate/datasource calls


                    
                    
                    addElements(_:rowView:didSelect:)

This method defaults many of the boilerplate callbacks needed to populate a UIPickerView when using an Array as a data source. The defaults that this method takes care of:

Provides the number of components
Provides the number of rows
Handles the pickerView(_:viewForRow:forComponent:) delegate method
Handles the pickerView(_:didSelectRow:inComponent:) delegate method

Important

An example of calling this method:

pickerView.addElements(
    <#myArray#>,
    rowView: { element, reuseView, component, row in
        return <#aView(from: element)#>},
    didSelect: { element, component, row in
        print("\(element) was selected")
)

Declaration

Swift

@discardableResult
public func addElements<Element>(_ elements: [Element],
                                 rowView: @escaping (_ element: Element, _ reuseView: UIView?, _ component: Int, _ row: Int) -> UIView,
                                 didSelect: @escaping (_ element: Element, _ component: Int, _ row: Int) -> Void) -> Self

Parameters

`strings`	An `Array` of any type to be used for each row in a single component picker view.
`rowView`	A closure that is called when the UIPickerView needs to display a view for it’s row.
`didSelect`	A closure that is called when the UIPickerView’s value has been selected.

Return Value

itself so you can daisy chain the other delegate/datasource calls


                    
                    
                    addComponents(_:didSelect:)

This method defaults many of the boilerplate callbacks needed to populate a UIPickerView when using a two-dimensional Array as a data source. The defaults that this method takes care of:

Provides the number of components
Provides the number of rows
Handles the pickerView(_:didSelectRow:inComponent:) delegate method
Provides the title string for each row

Important

An example of calling this method:

pickerView.addComponents(<#my2DArray#>) { aTitle,component,row in
    print("\(aTitle) was selected")
}

Declaration

Swift

@discardableResult
public func addComponents(_ strings: [[String]],
                          didSelect: @escaping (_ element: String, _ component: Int, _ row: Int) -> Void) -> Self

Parameters

`strings`	An `Array` of `Array` of `String`s to be used for each row and component in a picker view. The outer dimension of the array is the component (columns) and the inner dimension are the rows in that component. e.g. myTwoDArray[component][row]
`didSelect`	A closure that is called when the UIPickerView’s value has been selected.

Return Value

itself so you can daisy chain the other delegate/datasource calls


                    
                    
                    addComponents(_:rowTitle:didSelect:)

This method defaults many of the boilerplate callbacks needed to populate a UIPickerView when using a two-dimensional Array as a data source. The defaults that this method takes care of:

Provides the number of components
Provides the number of rows
Handles the pickerView(_:titleForRow:forComponent:) delegate method
Handles the pickerView(_:didSelectRow:inComponent:) delegate method

Important

An example of calling this method:

pickerView.addComponents(
    <#my2DArray#>,
    rowTitle: { element, component, row in
        return <#aTitle(from: element, componentIdx: component)#>},
    didSelect: { element, component, row in
        print("\(element) was selected")
)

Declaration

Swift

@discardableResult
public func addComponents<Element>(_ components: [[Element]],
                                   rowTitle: @escaping (_ element: Element, _ component: Int, _ row: Int) -> String,
                                   didSelect: @escaping (_ element: Element, _ component: Int, _ row: Int) -> Void) -> Self

Parameters

`components`	An `Array` of `Array` of any type to be used for each row and component in a picker view. The outer dimension of the array is the component (columns) and the inner dimension are the rows in that component. e.g. myTwoDArray[component][row]
`rowTitle`	A closure that is called when the UIPickerView needs to display a string for it’s row.
`didSelect`	A closure that is called when the UIPickerView’s value has been selected.

Return Value

itself so you can daisy chain the other delegate/datasource calls


                    
                    
                    addComponents(_:rowView:didSelect:)

This method defaults many of the boilerplate callbacks needed to populate a UIPickerView when using a two-dimensional Array as a data source. The defaults that this method takes care of:

Provides the number of components
Provides the number of rows
Handles the pickerView(_:viewForRow:forComponent:) delegate method
Handles the pickerView(_:didSelectRow:inComponent:) delegate method

Important

An example of calling this method:

pickerView.addComponents(
    <#my2DArray#>,
    rowView: { element, reuseView, component, row in
        return <#aView(from: element, componentIdx: component)#>},
    didSelect: { element, component, row in
        print("\(element) was selected")
)

parameter components: An Array of Array of any type to be used for each row and component in a picker view. The outer dimension of the array is the component (columns) and the inner dimension are the rows in that component. e.g. myTwoDArray[component][row]

Declaration

Swift

@discardableResult
public func addComponents<Element>(_ components: [[Element]],
                                   rowView: @escaping (_ element: Element, _ reuseView: UIView?, _ component: Int, _ row: Int) -> UIView,
                                   didSelect: @escaping (_ element: Element, _ component: Int, _ row: Int) -> Void) -> Self

Parameters

`rowView`	A closure that is called when the UIPickerView needs to display a view for it’s row.
`didSelect`	A closure that is called when the UIPickerView’s value has been selected.

Return Value

itself so you can daisy chain the other delegate/datasource calls

Delegate and DataSource Overrides


                    
                    
                    rowHeightForComponent(handler:)

Equivalent to implementing UIPickerViewDelegate’s pickerView(_:rowHeightForComponent:) method

Declaration

Swift

@discardableResult
public func rowHeightForComponent(handler: @escaping (_ component: Int) -> CGFloat) -> Self

Parameters


                                handler

The closure that will be called in place of its equivalent delegate method

Return Value

itself so you can daisy chain the other delegate calls


                    
                    
                    widthForComponent(handler:)

Equivalent to implementing UIPickerViewDelegate’s pickerView(_:widthForComponent:) method

Declaration

Swift

@discardableResult
public func widthForComponent(handler: @escaping (_ component: Int) -> CGFloat) -> Self

Parameters


                                handler

The closure that will be called in place of its equivalent delegate method

Return Value

itself so you can daisy chain the other delegate calls


                    
                    
                    titleForRow(handler:)

Equivalent to implementing UIPickerViewDelegate’s pickerView(_:titleForRow:forComponent:) method

Declaration

Swift

@discardableResult
public func titleForRow(handler: @escaping (_ row: Int, _ component: Int) -> String?) -> Self

Parameters


                                handler

The closure that will be called in place of its equivalent delegate method

Return Value

itself so you can daisy chain the other delegate calls


                    
                    
                    attributedTitleForRow(handler:)

Equivalent to implementing UIPickerViewDelegate’s pickerView(_:attributedTitleForRow:forComponent:) method

Declaration

Swift

@discardableResult
public func attributedTitleForRow(handler: @escaping (_ row: Int, _ component: Int) -> NSAttributedString?) -> Self

Parameters


                                handler

The closure that will be called in place of its equivalent delegate method

Return Value

itself so you can daisy chain the other delegate calls


                    
                    
                    viewForRow(handler:)

Equivalent to implementing UIPickerViewDelegate’s pickerView(_:viewForRow:forComponent:reusing:) method

Declaration

Swift

@discardableResult
public func viewForRow(handler: @escaping (_ row: Int, _ component: Int, _ reusingView: UIView?) -> UIView) -> Self

Parameters


                                handler

The closure that will be called in place of its equivalent delegate method

Return Value

itself so you can daisy chain the other delegate calls


                    
                    
                    didSelectRow(handler:)

Equivalent to implementing UIPickerViewDelegate’s pickerView(_:didSelectRow:inComponent:) method

Declaration

Swift

@discardableResult
public func didSelectRow(handler: @escaping (_ row: Int, _ component: Int) -> Void) -> Self

Parameters


                                handler

The closure that will be called in place of its equivalent delegate method

Return Value

itself so you can daisy chain the other delegate calls


                    
                    
                    numberOfComponents(handler:)

Equivalent to implementing UIPickerViewDataSource’s numberOfComponents(in:) method

Declaration

Swift

@discardableResult
public func numberOfComponents(handler: @escaping () -> Int) -> Self

Parameters


                                handler

The closure that will be called in place of its equivalent dataSource method

Return Value

itself so you can daisy chain the other dataSource calls


                    
                    
                    numberOfRowsInComponent(handler:)

Equivalent to implementing UIPickerViewDataSource’s pickerView(_:numberOfRowsInComponent:) method

Declaration

Swift

@discardableResult
public func numberOfRowsInComponent(handler: @escaping (_ component: Int) -> Int) -> Self

Parameters


                                handler

The closure that will be called in place of its equivalent dataSource method

Return Value

itself so you can daisy chain the other dataSource calls

Reset

clearClosureDelegates()
Clears any delegate/dataSource closures that were assigned to this UIPickerView. This cleans up memory as well as sets the delegate/dataSource properties to nil. This is typically only used for explicit cleanup. You are not required to call this method.
Declaration
Swift

@objc public func clearClosureDelegates()