I just create a new class in Swift, it's called myViewController
and it's a UIViewController
.
Now I'm trying to make it a UIPickerViewDelegate and DataSource but i got a strange error
import UIKit
class myViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {
...
}
It says Type "myViewController" does not conform to protocol UIPIckerDataSource
over the UIPickerViewDataSource.
Is it a bug of Xcode-Beta 3??
You need to implement all the required methods of UIPickerViewDataSource
and UIPickerViewDelegate
, if you want to conform to these protocols.
Swift is more like java when it comes to protocols because if you don't implement all the required methods declared by a protocol you are going to get a compile time error instead of a run time exception.
Fix-it in XCode 8.1 inserts a deprecated version of the method below if you're using Swift 3:
func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
return componentNumber
}
In XCode 10.0+
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return componentNumber
}
Implement required method of UIPickerDataSource
as in documentation.
The data source provides the picker view with the number of components, and the number of rows in each component, for displaying the picker view data. Both methods in this protocol are required.
So you need to implement these methods
func numberOfComponentsInPickerView(_ pickerView: UIPickerView!) -> Int {}
func pickerView(_ pickerView: UIPickerView!,
numberOfRowsInComponent component: Int) -> Int{}
My problem was that I had override
in front of the implementation function, where Swift doesn't consider protocol method implementations to be overrides (same). Just taking out the override
keyword fixed the issue.
My problem is protocol's method name is illegal,
@protocol ContactsSelectDelegate <NSObject>
- (void)selectContacts:(NSMutableArray *)contacts Tags:(NSMutableArray *)tags;
@end
Here, Tags:
should be tags:
.
I hope my answer is helpful.
来源:https://stackoverflow.com/questions/24970877/type-myviewcontroller-does-not-conform-to-protocol-uipickerdatasource-in-swift