an0

Call Chain:

CALayer.display() --- if delegate implements displayLayer ---> CALayerDelegate.displayLayer(:)
|                                                               /
|                                                              /
else                                                          /
|                                                            /
|                                                           |
v                                                           v
CALayer.drawInContext(:) ---> CALayerDelegate.drawLayer(:, inContext:) ---> UIView.drawRect(:)

an0

let q = Unicode.Scalar(34)!
let s =
"""
print("let q = Unicode.Scalar(34)!")
print("let s =")
print(q, q, q, separator: "")
print(s)
print(q, q, q, separator: "")
print(s)
"""

an0

let s=";print(\"let s=\"+s.debugDescription+s)";print("let s="+s.debugDescription+s)

an0

// Discussion: https://twitter.com/an0/status/644176341986856960

["a": "a"] as? [String: Any] // warning: conditional cast from '[String : Any]' to '[String : Any]' always succeeds

let a: Any = ["a": "a"]
let b = a as? [String: String]
let c = a as? [String: AnyObject]
let d = a as? [String: Any]

if let b = b {

an0

Keybase proof

I hereby claim:

• I am an0 on github.
• I am an0 (https://keybase.io/an0) on keybase.
• I have a public key ASCrKRZNGiZhsiJnfc9Ey5RkFBxrTSUvp-j2nwz_m3v-SQo

To claim this, I am signing this object:

an0

http://clang.llvm.org/docs/AutomaticReferenceCounting.html#self:

The self parameter variable of an Objective-C method is never actually retained by the implementation.

But http://clang.llvm.org/docs/AutomaticReferenceCounting.html#semantics:

For __weak objects, the current pointee is retained and then released at the end of the current full-expression. This must execute atomically with respect to assignments and to the final release of the pointee. For all other objects, the lvalue is loaded with primitive semantics.

The whole scheme makes weak references safer then strong references sometimes:

__block NSArray *strongArray = @[@1, @2];

an0

class Foo {
    
}

class Bar: Foo {
    
}

//let b: Bar? = nil
let b: Bar? = Bar()

an0

struct Foo {
    var i: Int = 0
}

var arr = [Foo(), Foo()]
print(arr)

for var a in arr {
    a.i = 1
}

an0

extension Character: ForwardIndexType {
    public func successor() -> Character {
        return Character(String(self).successor())
    }
}

extension String: ForwardIndexType {
    public func successor() -> String {
        let scalars = self.unicodeScalars
        let scalar = scalars[scalars.startIndex]

an0

// Source: https://twitter.com/AirspeedSwift/status/618546432954474497

prefix func !<T>(t: T?) -> T {
    return t ?? Array<Int8>(count: sizeof(T), repeatedValue: 0).withUnsafeBufferPointer {
        UnsafePointer($0.baseAddress).memory
    }
}

prefix func !<T: ExtensibleCollectionType>(t: T?) -> T {
    return t ?? T()