CODEWITHSUNDEEP
objective-ciosuidatepickerkey-value-observing
Chris
Chris

Reputation: 7310

Observing change in UIDatePicker

I noticed that there is no delegate to observe changes in UIDatePicker. Is there a way to detect when a change is made in the picker without confirming anything, like the moment it spins and lands on a new number I want to be able to detect that. I thought about key value observing, but I don't think there's a property that changes on the spot

Upvotes: 47

Views: 31948

Answers (4)

Argus
Argus

Reputation: 2339

Swift 4.2 | Xcode 10.1

@objc func handleDatePicker(_ datePicker: UIDatePicker) {
    textField.text = datePicker.date.formatted
}

override func viewDidLoad() {
    super.viewDidLoad()
    datePicker.addTarget(self, action: #selector(handleDatePicker), for: .valueChanged)
}

extension Date {
    static let formatter: DateFormatter = {
        let formatter = DateFormatter()
        formatter.dateFormat = "EEEE, dd MMM yyyy HH:mm:ss Z"
        return formatter
    }()
    var formatted: String {
        return Date.formatter.string(from: self)
    }
}

Upvotes: 11

Léo Natan
Léo Natan

Reputation: 57050

Here is a proposal for a KVO-compliant date picker:

@interface LNKVODatePicker : UIDatePicker

@end

@implementation LNKVODatePicker

- (void)willMoveToWindow:(UIWindow *)newWindow
{
    [super willMoveToWindow:newWindow];

    [self removeTarget:self action:@selector(_didChangeDate) forControlEvents:UIControlEventValueChanged];

    if(newWindow != nil)
    {
        [self addTarget:self action:@selector(_didChangeDate) forControlEvents:UIControlEventValueChanged];
    }
}

- (void)dealloc
{
    [self removeTarget:self action:@selector(_didChangeDate) forControlEvents:UIControlEventValueChanged];
}

- (void)_didChangeDate
{
    [self willChangeValueForKey:@"date"];
    [self didChangeValueForKey:@"date"];
}

@end

Upvotes: 2

Dustin
Dustin

Reputation: 6803

Go to IB and drag from the UIDatePicker to your .h file. Then selectenter image description here

Handle this however you want in your .m file; XCode will add the method below for you.

enter image description here

Upvotes: 44

chroman
chroman

Reputation: 1564

You need to add to your UIDatePicker the UIControlEventValueChanged event to handle date changes:

[myDatePicker addTarget:self action:@selector(dateIsChanged:) forControlEvents:UIControlEventValueChanged];

Then the implementation:

- (void)dateIsChanged:(id)sender{
     NSLog(@"Date changed");
}

Upvotes: 70

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