[_Nscftimer Copywithzone:]: Unrecognized Selector Sent to Instance

[__NSCFTimer copyWithZone:]: unrecognized selector sent to instance

The timer callback function must be either a function without arguments, or
a function taking a NSTimer as a single argument.

In your case, it should be

func doDelayedSearch(timer: NSTimer) {
    let searchText = timer.userInfo as String
    // ...
}

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Old answer: (The following is correct but does not apply here)

The target of the timer (self in your case) needs to be compatible with Objective-C,
i.e. derived from NSObject or marked with @objc.

See also
Exposing Swift Interfaces in Objective-C in the
"Using Swift with Cocoa and Objective-C" documentation (emphasis mine):

The @objc attribute makes your Swift API available in Objective-C and
the Objective-C runtime. In other words, you can use the @objc
attribute before any Swift method, property, subscript, initializer,
or class that you want to use from Objective-C code. If your class
inherits from an Objective-C class, the compiler inserts the attribute
for you.

...

This attribute is also useful when you’re working with
Objective-C classes that use selectors to implement the target-action design pattern—for example, NSTimer or UIButton.

Cocoa NSOutlineView bug - [NSCFTimer copyWithZone:]: unrecognized selector sent to instance

Sounds like an object is dying prematurely. You get the “unrecognized selector sent to instance” exception when a new object is allocated later with the same pointer and then something tries to send the old object a message (in the example shown, the reincarnation is an NSTimer and the message something tried to send the previous object was copyWithZone:). You get an EXC_BAD_ACCESS crash when the object is simply garbage memory.

Debug this by running your app under Instruments with the Zombies instrument enabled. The object will, instead of dying, become a zombie object. When something tries to send a zombie a message, the zombie will moan (figuratively speaking), which will show up in Instruments's timeline as a flag. You can click a button in that flag to view the history of the object, including all of its retentions and releases.

Unrecognized selector sent to instance with NSTimer.scheduledTimerWithTimeInterval function

You selector is "runCountDownFunction:". The colon is meaningful; it means this method takes one parameter. So you must make your method take one parameter. Declare your method like this:

func runCountDownFunction(timer:NSTimer) {

Now its signature matches the selector you gave when you created the timer.

Objective-C - NSTimer: unrecognized selector sent to class - call method from another class

You need to specify an instance of the Food class, so this argument is incorrect:

target:[Food class]

So what you are passing to NSTimer is a Class object, not a Food object.

Instead you probably need an instance variable of the Food instance and specify that:

@interface MyClass ()
{
    Food *_food;
}

@implementation MyClass
...
- (void)whatever
{
    _food = [Food new];             // This might need to be elsewhere
    SEL selector = @selector(addCloudOne);
    [NSTimer scheduledTimerWithTimeInterval:k1
                                     target:_food
                                   selector:selector
                                   userInfo:nil
                                    repeats:YES];
}

Swift NSTimer unrecognized selector sent to instance timerFireMethod

You've made a simple, yet common mistake.

Your method signature should be:

func timerFire(timer: NSTimer) {}

And your timer setup should be:

NSTimer(timeInterval: 1.0, target: self, selector: "timerFire:", userInfo: nil, repeats: true)

The mistake is that you're missing the colon in the selector name. timerFire is different from timerFire:. Skip the colon and it'll look for for a method like this:

func timerFire() {}

Without the NSTimer parameter. It's best though to include the parameter, and thus the colon, so that you can confirm the timer you get is the one you expect.

The same is true for notifications. If you're using Notification Center, include the colon, and the Notification object in the method.

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