retain count 調べ

obj.swift

class Obj2 {
    var tag: String
    init(_ tag: String) {
        self.tag = tag
    }
    
    func defer1() {
        print(tag, #function, "start", CFGetRetainCount(self))
        defer { print(tag, #function, "defer", CFGetRetainCount(self)) }
        print(tag, #function, "end", CFGetRetainCount(self))
    }
    
    func defer2() {
        print(tag, #function, "start", CFGetRetainCount(self))
        defer { print(tag, #function, "defer", CFGetRetainCount(self)) }
        defer { print(tag, #function, "defer", CFGetRetainCount(self)) }
        print(tag, #function, "end", CFGetRetainCount(self))
    }
    
    func deferNest() {
        print(tag, #function, "start", CFGetRetainCount(self))
        defer { [tag]
            print(tag, #function, "defer layer1", CFGetRetainCount(self))
            defer {
                print(tag, #function, "defer layer2", CFGetRetainCount(self))
            }
            print(tag, #function, "defer layer1", CFGetRetainCount(self))
        }
        print(tag, #function, "end", CFGetRetainCount(self))
    }
    
    func deferTagChange() {
        print(tag, #function, "start", CFGetRetainCount(self))
        defer { [tag]
            print(tag, #function, "defer", CFGetRetainCount(self))
        }
        tag = "change"
        print(tag, #function, "end", CFGetRetainCount(self))
    }
    
    func noescapeClosure() {
        print(tag, #function, "start", CFGetRetainCount(self))
        let closure: @noescape () -> Void = {
            print(tag, #function, "noescape closure", CFGetRetainCount(self))
        }
        closure()
        print(tag, #function, "end", CFGetRetainCount(self))
        closure()
    }
    
    func escapeClosure() {
        print(tag, #function, "start", CFGetRetainCount(self))
        let closure: () -> Void = {
            print(self.tag, #function, "noescape closure", CFGetRetainCount(self))
        }
        closure()
        print(tag, #function, "end", CFGetRetainCount(self))
        closure()
    }
    
    deinit {
        print(tag, "deinit", CFGetRetainCount(self))
        defer {
            print(tag, #function, "defer", CFGetRetainCount(self))
        }
    }
}

do {
    var obj = Obj2("first")
    print("--------------------------")
    obj.defer1()
    print("--------------------------")
    obj.defer2()
    print("--------------------------")
    obj.deferNest()
    print("--------------------------")
    obj.deferTagChange()
    print("--------------------------")
    obj.noescapeClosure()
    print("--------------------------")
    obj.escapeClosure()
    print("--------------------------")
    obj = Obj2("dummy")
}

/*
 --------------------------
 first defer1() start 3
 first defer1() end 3
 first defer1() defer 4
 --------------------------
 first defer2() start 3
 first defer2() end 3
 first defer2() defer 4
 first defer2() defer 4
 --------------------------
 first deferNest() start 3
 first deferNest() end 3
 first deferNest() defer layer1 4
 first deferNest() defer layer1 4
 first deferNest() defer layer2 5
 --------------------------
 first deferTagChange() start 3
 change deferTagChange() end 3
 change deferTagChange() defer 4
 --------------------------
 change noescapeClosure() start 3
 change noescapeClosure() noescape closure 5
 change noescapeClosure() end 4
 change noescapeClosure() noescape closure 5
 --------------------------
 change escapeClosure() start 3
 change escapeClosure() noescape closure 5
 change escapeClosure() end 4
 change escapeClosure() noescape closure 5
 --------------------------
 change deinit 1
 change deinit defer 2
 dummy deinit 1
 dummy deinit defer 2
 */

origin.swift

//: [Previous](@previous)

import Foundation

protocol RetainCountQuickLookable: CustomPlaygroundQuickLookable {}
extension RetainCountQuickLookable where Self: CFTypeRef {
    var customPlaygroundQuickLook: PlaygroundQuickLook {
        return .text("retain count: \(CFGetRetainCount(self))")
    }
}

class Obj: RetainCountQuickLookable {
    func function() {
        print(#function, "start", CFGetRetainCount(self))
        defer { print(#function, "defer", CFGetRetainCount(self)) }
        sleep(2)
        print(#function, "end", CFGetRetainCount(self))
    }
    
    deinit {
        print("deinit", CFGetRetainCount(self))
    }
}

do {
    var obj = Obj() as Optional
    print("create obj", CFGetRetainCount(obj))
    DispatchQueue.global().async { [weak obj] in
        print("before call", CFGetRetainCount(obj))
        obj?.function()
    }
    print("after dispatch", CFGetRetainCount(obj))
    obj = nil
    print("obj = nil")
}

//sleep(5)

print("end")


print("---------------------------------")
class Obj2: RetainCountQuickLookable {
    var tag: String
    init(_ tag: String) {
        self.tag = tag
    }
    
    func defer1() {
        print(tag, #function, "start", CFGetRetainCount(self))
        defer { print(tag, #function, "defer", CFGetRetainCount(self)) }
        print(tag, #function, "end", CFGetRetainCount(self))
    }
    
    func defer2() {
        print(tag, #function, "start", CFGetRetainCount(self))
        defer { print(tag, #function, "defer", CFGetRetainCount(self)) }
        defer { print(tag, #function, "defer", CFGetRetainCount(self)) }
        print(tag, #function, "end", CFGetRetainCount(self))
    }
    
    func deferNest() {
        print(tag, #function, "start", CFGetRetainCount(self))
        defer { [tag]
            print(tag, #function, "defer layer1", CFGetRetainCount(self))
            defer {
                print(tag, #function, "defer layer2", CFGetRetainCount(self))
            }
            print(tag, #function, "defer layer1", CFGetRetainCount(self))
        }
        print(tag, #function, "end", CFGetRetainCount(self))
    }
    
    func deferTagChange() {
        print(tag, #function, "start", CFGetRetainCount(self))
        defer { [tag]
            print(tag, #function, "defer", CFGetRetainCount(self))
        }
        tag = "change"
        print(tag, #function, "end", CFGetRetainCount(self))
    }
    
    func noescapeClosure() {
        print(tag, #function, "start", CFGetRetainCount(self))
        let closure: @noescape () -> Void = {
            print(tag, #function, "noescape closure", CFGetRetainCount(self))
        }
        closure()
        print(tag, #function, "end", CFGetRetainCount(self))
        closure()
    }
    
    func escapeClosure() {
        print(tag, #function, "start", CFGetRetainCount(self))
        let closure: () -> Void = {
            print(self.tag, #function, "noescape closure", CFGetRetainCount(self))
        }
        closure()
        print(tag, #function, "end", CFGetRetainCount(self))
        closure()
    }
    
    deinit {
        print(tag, "deinit", CFGetRetainCount(self))
        defer {
            print(tag, #function, "defer", CFGetRetainCount(self))
        }
    }
}

do {
    var obj = Obj2("first")
    print("--------------------------")
    obj.defer1()
    print("--------------------------")
    obj.defer2()
    print("--------------------------")
    obj.deferNest()
    print("--------------------------")
    obj.deferTagChange()
    print("--------------------------")
    obj.noescapeClosure()
    print("--------------------------")
    obj.escapeClosure()
    print("--------------------------")
    obj = Obj2("dummy")
}

/*
 --------------------------
 first defer1() start 3
 first defer1() end 3
 first defer1() defer 4
 --------------------------
 first defer2() start 3
 first defer2() end 3
 first defer2() defer 4
 first defer2() defer 4
 --------------------------
 first deferNest() start 3
 first deferNest() end 3
 first deferNest() defer layer1 4
 first deferNest() defer layer1 4
 first deferNest() defer layer2 5
 --------------------------
 first deferTagChange() start 3
 change deferTagChange() end 3
 change deferTagChange() defer 4
 --------------------------
 change noescapeClosure() start 3
 change noescapeClosure() noescape closure 5
 change noescapeClosure() end 4
 change noescapeClosure() noescape closure 5
 --------------------------
 change escapeClosure() start 3
 change escapeClosure() noescape closure 5
 change escapeClosure() end 4
 change escapeClosure() noescape closure 5
 --------------------------
 change deinit 1
 change deinit defer 2
 dummy deinit 1
 dummy deinit defer 2
 */



//: [Next](@next)