class TestObject { // No need to inherit from NSObject.
    // Use `@objc` to make this method accessible from Objective-C
    // Using `dynamic` tells Swift to always refer to Objective-C dynamic dispatch
    @objc dynamic func testMethod() {
        print("Executing `testMethod`")
    }
}

let obj = TestObject()

let token = try hookBefore(object: obj, selector: #selector(TestObject.testMethod)) {
    print("Before executing `testMethod`")
}

obj.testMethod()
token.cancelHook() // cancel the hook

class TestObject {
    @objc dynamic func testMethod(_ parameter: String) {
        print("Executing `testMethod` with parameter: \(parameter)")
    }
}

let obj = TestObject()

let token = try hookAfter(object: obj, selector: #selector(TestObject.testMethod(_:)), closure: { obj, sel, parameter in
    print("After executing `testMethod` with parameter: \(parameter)")
} as @convention(block) ( // Using `@convention(block)` to declares a Swift closure as an Objective-C block
    AnyObject, // `obj` Instance
    Selector, // `testMethod` Selector
    String // first parameter
) -> Void // return value
)

obj.testMethod("ABC")
token.cancelHook() // cancel the hook

class Math {
    @objc dynamic func double(_ number: Int) -> Int {
        let result = number * 2
        print("Executing `double` with \(number), result is \(result)")
        return result
    }
}

let math = Math()

try hookInstead(object: math, selector: #selector(Math.double(_:)), closure: { original, obj, sel, number in
    print("Before executing `double`")
    let originalResult = original(obj, sel, number)
    print("After executing `double`, got result \(originalResult)")
    print("Triple the number!")
    return number * 3
} as @convention(block) (
    (AnyObject, Selector, Int) -> Int,  // original method block
    AnyObject, // `math` Instance
    Selector, // `sum` Selector
    Int // number
) -> Int // return value
)

let number = 3
let result = math.double(number)
print("Double \(number), got \(result)")

class TestObject {
    @objc dynamic func testMethod() {
        print("Executing `testMethod`")
    }
}

let token = try hookBefore(targetClass: TestObject.self, selector: #selector(TestObject.testMethod)) {
    print("Before executing `testMethod`")
}

let obj = TestObject()
obj.testMethod()
token.cancelHook() // cancel the hook

class TestObject {
    @objc dynamic class func testClassMethod() {
        print("Executing `testClassMethod`")
    }
    @objc dynamic static func testStaticMethod() {
        print("Executing `testStaticMethod`")
    }
}

try hookClassMethodBefore(targetClass: TestObject.self, selector: #selector(TestObject.testClassMethod)) {
    print("Before executing `testClassMethod`")
}
TestObject.testClassMethod()

try hookClassMethodBefore(targetClass: TestObject.self, selector: #selector(TestObject.testStaticMethod)) {
    print("Before executing `testStaticMethod`")
}
TestObject.testStaticMethod()