以编程方式打开/关闭 UISwitch iOS

Question

I have a UISwitch embedded in UITableviewCell. The tableview uses dynamic prototype cells. The following code controls the switch action when selected. It works good and turns the switch on and off and runs the code. However, when I programmatically call the button action, it runs the code but doesn't not change the selected position from off to on or vice versa. Why would it not show the switch ON/OFF change?

// Call button programmatically

    [self didHideFlags:self];

    - (IBAction)didHideFlags:(id)sender{
    _isOnFlag = !_isOnFlag;
    if (_isOnFlag){
        [self.flagOverlay.graphics removeAllObjects];
        [self.flagTableView reloadData];
    }else{
        NSLog(@"Option 2");
        [self updateMyFlagsWitAlert:NO];
    }
}

Answer 1

Create IBOutlet for your UISwitch and when you call the action programmatically use it as sender, Or you can do it yourself when the action is triggered just change change UISwitch selected state manually,

Hope this will help.

Answer 2

The action method responds to a change in the switch's state, but the calling the action method yourself won't change the switch state.

You need to set the switch's isOn property to turn it on or off.

Answer 3

UISwitch subclasses UIControl . Using Interface Builder, you've effectively added an action method named didHideFlags(_:) for the UIEvent.valueChanged event with a target equal to whichever instance implements the didHideFlags(_:) function:

switch.addTarget(<myTarget>, action: #selector(didHideFlags(_:)), for controlEvents: .valueChanged)

From the UIControl documentation ( The Target-Action Mechanism ):

Controls use the target-action mechanism to report interesting events happening to your code. The target-action mechanism simplifies the code that you write to use controls in your app. Instead of writing code to track touch events, you write action methods to respond to control-specific events. For example, you might write an action method that responds to changes in the value of a slider. The control handles all the work of tracking incoming touch events and determining when to call your methods.

Action methods are not responsible for causing a UIControl 's standard behavior, such as a UISwitch toggling on or off. Rather, action methods implement side effects that occur in response to events.

As Paulw11 suggests , to programmatically toggle the UISwitch on or off, mutate its isOn property or call its setOn(_:animated:) method:

switch.isOn = false

or

switch.setOn(false, animated: true)