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!!Introspec+ng!Swi0!"
dotSwi'(2015,(JP(Simard,(@simjp
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Why?
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Mantle
@interface GHIssue : MTLModel
@property GHUser *assignee;
@property NSDate *updatedAt;
@property NSString *title;
@property NSString *body;
@property NSDate *retrievedAt;
@end
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FCModel(&(Realm
@interface Employee : RLMObject
@property NSString *name;
@property NSDate *startDate;
@property float salary;
@property BOOL fullTime;
@end
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How?
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The$six$ways$to$introspect*Swi-
1. S$ck'with'compile1$me'types'&'constraints
2. Apply'dynamic'cas$ng
3. Leverage'Swi?'s'MirrorType
4. Abuse'Objec$ve1C's'run$me
5. Use'private'func$ons
6. Resort'to'inspec$ng'memory'layout
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The$six$degrees$of$evil
1. S$ck'with'compile1$me'types'&'constraints'–'!
2. Apply'dynamic'cas$ng'–'"
3. Leverage'Swi@'s'MirrorType'–'#
4. Abuse'Objec$ve1C's'run$me'–'$
5. Use'private'func$ons'–'%
6. Resort'to'inspec$ng'memory'layout'–'&
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Compile()me
Types&&&Constraints
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QueryKit
struct MyStruct {
let intProp: Int
struct Attributes {
static let intProp = Attribute("intProp")
}
}
// Usage
let intProp = MyStruct.Attributes.intProp
intProp > 0 // NSPredicate("intProp > 0"), typesafe
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Argo
extension User: JSONDecodable {
static func create(name: String)(email: String?)(role: Role)
(friends: [User]) -> User {
return User(name: name, email: email, role: role, friends: friends)
}
static func decode(j: JSONValue) -> User? {
return User.create
<^> j <| "name"
<*> j <|? "email" // Use ? for parsing optional values
<*> j <| "role" // Custom types conforming to JSONDecodable work
<*> j <|| "friends" // parse arrays of objects
}
}
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Dynamic
Cas$ng
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as?
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protocol XPCConvertible {}
extension Int64: XPCConvertible {}
extension String: XPCConvertible {}
func toXPC(object: XPCConvertible) -> xpc_object_t? {
switch(object) {
case let object as Int64:
return xpc_int64_create(object)
case let object as String:
return xpc_string_create(object)
default:
fatalError("Unsupported type for object: \(object)")
return nil
}
}
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Official
Swi$
Reflec%on
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/// The type returned by `reflect(x)`; supplies an API for runtime reflection on `x`
protocol MirrorType {
/// The instance being reflected
var value: Any { get }
/// Identical to `value.dynamicType`
var valueType: Any.Type { get }
/// A unique identifier for `value` if it is a class instance; `nil` otherwise.
var objectIdentifier: ObjectIdentifier? { get }
/// The count of `value`\ 's logical children
var count: Int { get }
subscript (i: Int) -> (String, MirrorType) { get }
/// A string description of `value`.
var summary: String { get }
/// A rich representation of `value` for an IDE, or `nil` if none is supplied.
var quickLookObject: QuickLookObject? { get }
/// How `value` should be presented in an IDE.
var disposition: MirrorDisposition { get }
}
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struct MyStruct {
let stringProp: String
let intProp: Int
}
let reflection = reflect(MyStruct(stringProp: "a", intProp: 1))
for i in 0..
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Objec&ve(C
Run$me
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import Foundation
class objcSub: NSObject {
let string: String?
let int: Int?
}
var propCount: UInt32 = 0
let properties = clazz_copyPropertyList(objcSub.self, &propCount)
for i in 0.. "string"
String.fromCString(property_getAttributes(prop))! // => "T@,N,R,Vstring"
}
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Using
Private
Func%ons
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nm -a libswiftCore.dylib | grep "stdlib"
> ...
> __TFSs28_stdlib_getDemangledTypeNameU__FQ_SS
> ...
> _swift_stdlib_conformsToProtocol
> _swift_stdlib_demangleName
> _swift_stdlib_dynamicCastToExistential1
> _swift_stdlib_dynamicCastToExistential1Unconditional
> _swift_stdlib_getTypeName
> ...
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struct MyStruct {
let stringProp: String
let intProp: Int
}
let reflection = reflect(MyStruct(stringProp: "a", intProp: 1))
for i in 0..
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Inspec'ng
Memory
Layout
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struct _swift_data {
unsigned long flags;
const char *className;
int fieldcount, flags2;
const char *ivarNames;
struct _swift_field **(*get_field_data)();
};
struct _swift_class {
union {
Class meta;
unsigned long flags;
};
Class supr;
void *buckets, *vtable, *pdata;
int f1, f2; // added for Beta5
int size, tos, mdsize, eight;
struct _swift_data *swiftData;
IMP dispatch[1];
};
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class GenericClass {}
class SimpleClass: NSObject {}
class ParentClass {
let boolProp: Bool? // Optionals
let intProp: Int // Without default value
var floatProp = 0 as Float // With default value
var doubleProp = 0.0
var stringProp = ""
var simpleProp = SimpleClass()
var genericProp = GenericClass()
}
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{
"boolProp": "b",
"intProp": "i",
"floatProp": "f",
"doubleProp": "d",
"stringProp": "S",
"simpleProp": "ModuleName.SimpleClass",
"genericProp": "[Mangled GenericClass]"
}
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Why?
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RealmSwi)
class Employee: Object {
dynamic var name = "" // you can specify defaults
dynamic var startDate = NSDate()
dynamic var salary = 0.0
dynamic var fullTime = true
}
class Company: Object {
dynamic var name = ""
dynamic var ceo: Employee? // optional
let employees = List()
}
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The$six$ways$to$introspect*Swi-
1. S$ck'with'compile1$me'types'&'constraints'–'!
2. Apply'dynamic'cas$ng'–'"
3. Leverage'Swi@'s'MirrorType'–'#
4. Abuse'Objec$ve1C's'run$me'–'$
5. Use'private'func$ons'–'%
6. Resort'to'inspec$ng'memory'layout'–'&
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Links&(1/2)
• This&talk:&github.com/jpsim/talks
• Mantle:&github.com/Mantle/Mantle
• FCModel:&github.com/marcoarment/FCModel
• Realm:&github.com/realm/realm9cocoa
• QueryKit:&github.com/QueryKit/QueryKit
• Argo:&github.com/thoughtbot/Argo
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Links&(2/2)
• Dynamic)Cas,ng:)blog.segiddins.me
• Swi1XPC:)github.com/jpsim/Swi5XPC
• MirrorType)Docs:)swi5doc.org/protocol/MirrorType
• Russ)Bishop)on)horrible)things:)russbishop.net
• Injec,on)for)Xcode:)injec=onforxcode.com
• Swi1IvarTypeDetector:)github.com/jpsim/Swi5IvarTypeDetector
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Thank&You!
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dotSwift().questions?.askThem!
JP#Simard,#@simjp,#realm.io
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