۲۲
آبان

جلسه ۳۰ : قالب بندی نوع در Swift

دسته‌بندی‌ها :

جزئیات
نوع محتواآموزش تصویری

فهرست

مقدمه

با عرض سلام و وقت بخیر خدمت کاربران سایت پی وی لرن . و کاربرانی که دوره کامل آموزش Swift را دنبال می کنند. قالب بندی نوع یا مفهوم Type Casting در Swift با حفظ مقدار یک خصوصیت نوع آن را به نوعی دیگر تبدیل می کند، به عنوان مثال زمانیکه شما یک مقدار عددی را در یک مقدار متغیر رشته ای قرار می دهید یا به مقدار رشته ای اضافه می کنید به طور خودکار نوع عددی به نوع رشته تبدیل شده اما مقدار آن حفظ می شود. مفهوم قالب بندی نوع در Swift دو نوع عملگر ‘is’ برای چک کردن نوع یک مقدار و ‘as’ را برای تبدیل نوع یک مقدار به نوع دیگر را ارائه می دهد، در ادامه ی این مبحث برای آشنایی بیشتر با مفهوم Type Casting در Swift با ما همراه باشید.

قالب بندی نوع در Swift

در ادامه ی این آموزش شما را با فرآیند Type Casting در Swift و مفاهیم آن آشنا می کنیم.

تعریف یک سلسله مراتب کلاس

مفهوم قالب بندی نوع در Swift استفاده می شود که نوع نمونه ها را چک کند تا معلوم شود آیا به یک نوع خاص کلاس تعلق دارد یا خیر.

همچنین سلسله مراتب کلاس ها و کلاس های آن را بررسی می کند.

مثال :

class Subjects {
   var physics: String
   init(physics: String) {
      self.physics = physics
   }
}

class Chemistry: Subjects {
   var equations: String
   init(physics: String, equations: String) {
      self.equations = equations
      super.init(physics: physics)
   }
}

class Maths: Subjects {
   var formulae: String
   init(physics: String, formulae: String) {
      self.formulae = formulae
      super.init(physics: physics)
   }
}

let sa = [ Chemistry(physics: "solid physics", equations: "Hertz"),
   Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz")]

let samplechem = Chemistry(physics: "solid physics", equations: "Hertz")
print("Instance physics is: \(samplechem.physics)")
print("Instance equation is: \(samplechem.equations)")

let samplemaths = Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz")
print("Instance physics is: \(samplemaths.physics)")
print("Instance formulae is: \(samplemaths.formulae)")

class Subjects {

var physics: String

init(physics: String) {

self.physics = physics

}

class Chemistry: Subjects {

var equations: String

init(physics: String, equations: String) {

self.equations = equations

super.init(physics: physics)

}

class Maths: Subjects {

var formulae: String

init(physics: String, formulae: String) {

self.formulae = formulae

super.init(physics: physics)

}

let sa = [ Chemistry(physics: "solid physics", equations: "Hertz"),

Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz")]

let samplechem = Chemistry(physics: "solid physics", equations: "Hertz")

print("Instance physics is: \(samplechem.physics)")

print("Instance equation is: \(samplechem.equations)")

let samplemaths = Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz")

print("Instance physics is: \(samplemaths.physics)")

print("Instance formulae is: \(samplemaths.formulae)")

نتیجه ی کامپایل و اجرای کد فوق به صورت زیر خواهد بود:

مثال :

Instance physics is: solid physics
Instance equation is: Hertz
Instance physics is: Fluid Dynamics
Instance formulae is: Giga Hertz

Instance physics is: solid physics

Instance equation is: Hertz

Instance physics is: Fluid Dynamics

Instance formulae is: Giga Hertz

بررسی نوع

بررسی نوع با عملگر ‘is’ انجام می شود. در صورتی که نمونه به زیر کلاس خاصی متعلق باشد مقدار ‘true’ و در غیر این صورت ‘false’ را برمی گرداند.

مثال :

class Subjects {
   var physics: String
   init(physics: String) {
      self.physics = physics
   }
}

class Chemistry: Subjects {
   var equations: String
   init(physics: String, equations: String) {
      self.equations = equations
      super.init(physics: physics)
   }
}

class Maths: Subjects {
   var formulae: String
   init(physics: String, formulae: String) {
      self.formulae = formulae
      super.init(physics: physics)
   }
}

let sa = [
   Chemistry(physics: "solid physics", equations: "Hertz"),
   Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz"),
   Chemistry(physics: "Thermo physics", equations: "Decibels"),
   Maths(physics: "Astro Physics", formulae: "MegaHertz"),
   Maths(physics: "Differential Equations", formulae: "Cosine Series")]

let samplechem = Chemistry(physics: "solid physics", equations: "Hertz")
print("Instance physics is: \(samplechem.physics)")
print("Instance equation is: \(samplechem.equations)")

let samplemaths = Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz")
print("Instance physics is: \(samplemaths.physics)")
print("Instance formulae is: \(samplemaths.formulae)")

var chemCount = 0
var mathsCount = 0
for item in sa {
   if item is Chemistry {
      ++chemCount
   } else if item is Maths {
      ++mathsCount
   }
}

print("Subjects in chemistry contains \(chemCount) topics and maths contains \(mathsCount) topics")

class Subjects {

var physics: String

init(physics: String) {

self.physics = physics

}

class Chemistry: Subjects {

var equations: String

init(physics: String, equations: String) {

self.equations = equations

super.init(physics: physics)

}

class Maths: Subjects {

var formulae: String

init(physics: String, formulae: String) {

self.formulae = formulae

super.init(physics: physics)

}

let sa = [

Chemistry(physics: "solid physics", equations: "Hertz"),

Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz"),

Chemistry(physics: "Thermo physics", equations: "Decibels"),

Maths(physics: "Astro Physics", formulae: "MegaHertz"),

Maths(physics: "Differential Equations", formulae: "Cosine Series")]

let samplechem = Chemistry(physics: "solid physics", equations: "Hertz")

print("Instance physics is: \(samplechem.physics)")

print("Instance equation is: \(samplechem.equations)")

let samplemaths = Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz")

print("Instance physics is: \(samplemaths.physics)")

print("Instance formulae is: \(samplemaths.formulae)")

var chemCount = 0

var mathsCount = 0

for item in sa {

if item is Chemistry {

++chemCount

} else if item is Maths {

++mathsCount

}

print("Subjects in chemistry contains \(chemCount) topics and maths contains \(mathsCount) topics")

نتیجه ی کامپایل و اجرای کد فوق به صورت زیر خواهد بود:

مثال :

Instance physics is: solid physics
Instance equation is: Hertz
Instance physics is: Fluid Dynamics
Instance formulae is: Giga Hertz
Subjects in chemistry contains 2 topics and maths contains 3 topics

Instance physics is: solid physics

Instance equation is: Hertz

Instance physics is: Fluid Dynamics

Instance formulae is: Giga Hertz

Subjects in chemistry contains 2 topics and maths contains 3 topics

نفوذپذیری

نفوذپذیری نوع زیر کلاس می تواند با دو زیر کلاس (as? و as!) انجام شود.

عملگر ‘as?’ زمانیکه مقدار nil بازگردانده شود یک مقدار اختیاری را برمی گرداند.

زمانی که مقدار downcasting مقدار nil را بر می گرداند، force unwrapping را همانطور که در مبحث optional chaining بررسی کردیم باز می گرداند.

این مورد در زمان اجرا در صورت عدم اجرای موفق، خطای زمان اجرا را نمایش می دهد.

مثال :

class Subjects {
   var physics: String
   init(physics: String) {
      self.physics = physics
   }
}

class Chemistry: Subjects {
   var equations: String
   init(physics: String, equations: String) {
      self.equations = equations
      super.init(physics: physics)
   }
}

class Maths: Subjects {
   var formulae: String
   init(physics: String, formulae: String) {
      self.formulae = formulae
      super.init(physics: physics)
   }
}

let sa = [
   Chemistry(physics: "solid physics", equations: "Hertz"),
   Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz"),
   Chemistry(physics: "Thermo physics", equations: "Decibels"),
   Maths(physics: "Astro Physics", formulae: "MegaHertz"),
   Maths(physics: "Differential Equations", formulae: "Cosine Series")]

let samplechem = Chemistry(physics: "solid physics", equations: "Hertz")
print("Instance physics is: \(samplechem.physics)")
print("Instance equation is: \(samplechem.equations)")

let samplemaths = Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz")
print("Instance physics is: \(samplemaths.physics)")
print("Instance formulae is: \(samplemaths.formulae)")

var chemCount = 0
var mathsCount = 0

for item in sa {
   if let print = item as? Chemistry {
      print("Chemistry topics are: '\(print.physics)', \(print.equations)")
   } else if let example = item as? Maths {
      print("Maths topics are: '\(example.physics)', \(example.formulae)")
   }
}

class Subjects {

var physics: String

init(physics: String) {

self.physics = physics

}

class Chemistry: Subjects {

var equations: String

init(physics: String, equations: String) {

self.equations = equations

super.init(physics: physics)

}

class Maths: Subjects {

var formulae: String

init(physics: String, formulae: String) {

self.formulae = formulae

super.init(physics: physics)

}

let sa = [

Chemistry(physics: "solid physics", equations: "Hertz"),

Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz"),

Chemistry(physics: "Thermo physics", equations: "Decibels"),

Maths(physics: "Astro Physics", formulae: "MegaHertz"),

Maths(physics: "Differential Equations", formulae: "Cosine Series")]

let samplechem = Chemistry(physics: "solid physics", equations: "Hertz")

print("Instance physics is: \(samplechem.physics)")

print("Instance equation is: \(samplechem.equations)")

let samplemaths = Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz")

print("Instance physics is: \(samplemaths.physics)")

print("Instance formulae is: \(samplemaths.formulae)")

var chemCount = 0

var mathsCount = 0

for item in sa {

if let print = item as? Chemistry {

print("Chemistry topics are: '\(print.physics)', \(print.equations)")

} else if let example = item as? Maths {

print("Maths topics are: '\(example.physics)', \(example.formulae)")

}

نتیجه ی کامپایل و اجرای کد فوق به صورت زیر خواهد بود:

مثال :

Instance physics is: solid physics
Instance equation is: Hertz
Instance physics is: Fluid Dynamics
Instance formulae is: Giga Hertz
Chemistry topics are: 'solid physics', Hertz
Maths topics are: 'Fluid Dynamics', Giga Hertz
Chemistry topics are: 'Thermo physics', Decibels
Maths topics are: 'Astro Physics', MegaHertz
Maths topics are: 'Differential Equations', Cosine Series

Instance physics is: solid physics

Instance equation is: Hertz

Instance physics is: Fluid Dynamics

Instance formulae is: Giga Hertz

Chemistry topics are: 'solid physics', Hertz

Maths topics are: 'Fluid Dynamics', Giga Hertz

Chemistry topics are: 'Thermo physics', Decibels

Maths topics are: 'Astro Physics', MegaHertz

Maths topics are: 'Differential Equations', Cosine Series

کلید واژه ی Any در Typecasting

کلمه کلیدی ‘Any’ برای نشان دادن نمونه ای که متعلق به هر نوع از جمله انواع توابع می باشد استفاده می شود.

مثال :

class Subjects {
   var physics: String
   init(physics: String) {
      self.physics = physics
   }
}

class Chemistry: Subjects {
   var equations: String
   init(physics: String, equations: String) {
      self.equations = equations
      super.init(physics: physics)
   }
}

class Maths: Subjects {
   var formulae: String
   init(physics: String, formulae: String) {
      self.formulae = formulae
      super.init(physics: physics)
   }
}

let sa = [
   Chemistry(physics: "solid physics", equations: "Hertz"),
   Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz"),
   Chemistry(physics: "Thermo physics", equations: "Decibels"),
   Maths(physics: "Astro Physics", formulae: "MegaHertz"),
   Maths(physics: "Differential Equations", formulae: "Cosine Series")]

let samplechem = Chemistry(physics: "solid physics", equations: "Hertz")
print("Instance physics is: \(samplechem.physics)")
print("Instance equation is: \(samplechem.equations)")

let samplemaths = Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz")
print("Instance physics is: \(samplemaths.physics)")
print("Instance formulae is: \(samplemaths.formulae)")

var chemCount = 0
var mathsCount = 0

for item in sa {
   if let print = item as? Chemistry {
      print("Chemistry topics are: '\(print.physics)', \(print.equations)")
   } else if let example = item as? Maths {
      print("Maths topics are: '\(example.physics)', \(example.formulae)")
   }
}

var exampleany = [Any]()

exampleany.append(12)
exampleany.append(3.14159)
exampleany.append("Example for Any")
exampleany.append(Chemistry(physics: "solid physics", equations: "Hertz"))

for print in exampleany {
   switch print {
      case let someInt as Int:
         print("Integer value is \(someInt)")
      case let someDouble as Double where someDouble > 0:
         print("Pi value is \(someDouble)")
      case let someString as String:
         print("\(someString)")
      case let phy as Chemistry:   
         print("Topics '\(phy.physics)', \(phy.equations)")
      default:
         print("None")
   }
}

class Subjects {

var physics: String

init(physics: String) {

self.physics = physics

}

class Chemistry: Subjects {

var equations: String

init(physics: String, equations: String) {

self.equations = equations

super.init(physics: physics)

}

class Maths: Subjects {

var formulae: String

init(physics: String, formulae: String) {

self.formulae = formulae

super.init(physics: physics)

}

let sa = [

Chemistry(physics: "solid physics", equations: "Hertz"),

Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz"),

Chemistry(physics: "Thermo physics", equations: "Decibels"),

Maths(physics: "Astro Physics", formulae: "MegaHertz"),

Maths(physics: "Differential Equations", formulae: "Cosine Series")]

let samplechem = Chemistry(physics: "solid physics", equations: "Hertz")

print("Instance physics is: \(samplechem.physics)")

print("Instance equation is: \(samplechem.equations)")

let samplemaths = Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz")

print("Instance physics is: \(samplemaths.physics)")

print("Instance formulae is: \(samplemaths.formulae)")

var chemCount = 0

var mathsCount = 0

for item in sa {

if let print = item as? Chemistry {

print("Chemistry topics are: '\(print.physics)', \(print.equations)")

} else if let example = item as? Maths {

print("Maths topics are: '\(example.physics)', \(example.formulae)")

}

var exampleany = [Any]()

exampleany.append(12)

exampleany.append(3.14159)

exampleany.append("Example for Any")

exampleany.append(Chemistry(physics: "solid physics", equations: "Hertz"))

for print in exampleany {

switch print {

case let someInt as Int:

print("Integer value is \(someInt)")

case let someDouble as Double where someDouble > 0:

print("Pi value is \(someDouble)")

case let someString as String:

print("\(someString)")

case let phy as Chemistry:

print("Topics '\(phy.physics)', \(phy.equations)")

default:

print("None")

}

نتیجه ی کامپایل و اجرای کد فوق به صورت زیر خواهد بود:

مثال :

Instance physics is: solid physics
Instance equation is: Hertz
Instance physics is: Fluid Dynamics
Instance formulae is: Giga Hertz
Chemistry topics are: 'solid physics', Hertz
Maths topics are: 'Fluid Dynamics', Giga Hertz
Chemistry topics are: 'Thermo physics', Decibels
Maths topics are: 'Astro Physics', MegaHertz
Maths topics are: 'Differential Equations', Cosine Series
Integer value is 12
Pi value is 3.14159
Example for Any
Topics 'solid physics', Hertz

Instance physics is: solid physics

Instance equation is: Hertz

Instance physics is: Fluid Dynamics

Instance formulae is: Giga Hertz

Chemistry topics are: 'solid physics', Hertz

Maths topics are: 'Fluid Dynamics', Giga Hertz

Chemistry topics are: 'Thermo physics', Decibels

Maths topics are: 'Astro Physics', MegaHertz

Maths topics are: 'Differential Equations', Cosine Series

Integer value is 12

Pi value is 3.14159

Example for Any

Topics 'solid physics', Hertz

کلمه کلیدی AnyObject

برای نشان دادن نمونه ای از هر نوع کلاس، از کلید واژه ی AnyObject استفاده می شود.

مثال :

class Subjects {
   var physics: String
   init(physics: String) {
      self.physics = physics
   }
}

class Chemistry: Subjects {
   var equations: String
   init(physics: String, equations: String) {
      self.equations = equations
      super.init(physics: physics)
   }
}

class Maths: Subjects {
   var formulae: String
   init(physics: String, formulae: String) {
      self.formulae = formulae
      super.init(physics: physics)
   }
}

let saprint: [AnyObject] = [Chemistry(physics: "solid physics", equations: "Hertz"),
   Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz"),
   Chemistry(physics: "Thermo physics", equations: "Decibels"),
   Maths(physics: "Astro Physics", formulae: "MegaHertz"),
   Maths(physics: "Differential Equations", formulae: "Cosine Series")]

let samplechem = Chemistry(physics: "solid physics", equations: "Hertz")
print("Instance physics is: \(samplechem.physics)")
print("Instance equation is: \(samplechem.equations)")

let samplemaths = Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz")
print("Instance physics is: \(samplemaths.physics)")
print("Instance formulae is: \(samplemaths.formulae)")

var chemCount = 0
var mathsCount = 0

for item in saprint {
   if let print = item as? Chemistry {
      print("Chemistry topics are: '\(print.physics)', \(print.equations)")
   } else if let example = item as? Maths {
      print("Maths topics are: '\(example.physics)', \(example.formulae)")
   }
}

var exampleany = [Any]()
exampleany.append(12)
exampleany.append(3.14159)
exampleany.append("Example for Any")
exampleany.append(Chemistry(physics: "solid physics", equations: "Hertz"))

for print in exampleany {
   switch print {
      case let someInt as Int:
         print("Integer value is \(someInt)")
      case let someDouble as Double where someDouble > 0:
         print("Pi value is \(someDouble)")
      case let someString as String:
         print("\(someString)")
      case let phy as Chemistry:
         print("Topics '\(phy.physics)', \(phy.equations)")
      default:
         print("None")
   }
}

class Subjects {

var physics: String

init(physics: String) {

self.physics = physics

}

class Chemistry: Subjects {

var equations: String

init(physics: String, equations: String) {

self.equations = equations

super.init(physics: physics)

}

class Maths: Subjects {

var formulae: String

init(physics: String, formulae: String) {

self.formulae = formulae

super.init(physics: physics)

}

let saprint: [AnyObject] = [Chemistry(physics: "solid physics", equations: "Hertz"),

Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz"),

Chemistry(physics: "Thermo physics", equations: "Decibels"),

Maths(physics: "Astro Physics", formulae: "MegaHertz"),

Maths(physics: "Differential Equations", formulae: "Cosine Series")]

let samplechem = Chemistry(physics: "solid physics", equations: "Hertz")

print("Instance physics is: \(samplechem.physics)")

print("Instance equation is: \(samplechem.equations)")

let samplemaths = Maths(physics: "Fluid Dynamics", formulae: "Giga Hertz")

print("Instance physics is: \(samplemaths.physics)")

print("Instance formulae is: \(samplemaths.formulae)")

var chemCount = 0

var mathsCount = 0

for item in saprint {

if let print = item as? Chemistry {

print("Chemistry topics are: '\(print.physics)', \(print.equations)")

} else if let example = item as? Maths {

print("Maths topics are: '\(example.physics)', \(example.formulae)")

}

var exampleany = [Any]()

exampleany.append(12)

exampleany.append(3.14159)

exampleany.append("Example for Any")

exampleany.append(Chemistry(physics: "solid physics", equations: "Hertz"))

for print in exampleany {

switch print {

case let someInt as Int:

print("Integer value is \(someInt)")

case let someDouble as Double where someDouble > 0:

print("Pi value is \(someDouble)")

case let someString as String:

print("\(someString)")

case let phy as Chemistry:

print("Topics '\(phy.physics)', \(phy.equations)")

default:

print("None")

}

نتیجه ی کامپایل و اجرای کد فوق به صورت زیر خواهد بود:

مثال :

Instance physics is: solid physics
Instance equation is: Hertz
Instance physics is: Fluid Dynamics
Instance formulae is: Giga Hertz
Chemistry topics are: 'solid physics', Hertz
Maths topics are: 'Fluid Dynamics', Giga Hertz
Chemistry topics are: 'Thermo physics', Decibels
Maths topics are: 'Astro Physics', MegaHertz
Maths topics are: 'Differential Equations', Cosine Series
Integer value is 12
Pi value is 3.14159
Example for Any
Topics 'solid physics', Hertz

Instance physics is: solid physics

Instance equation is: Hertz

Instance physics is: Fluid Dynamics

Instance formulae is: Giga Hertz

Chemistry topics are: 'solid physics', Hertz

Maths topics are: 'Fluid Dynamics', Giga Hertz

Chemistry topics are: 'Thermo physics', Decibels

Maths topics are: 'Astro Physics', MegaHertz

Maths topics are: 'Differential Equations', Cosine Series

Integer value is 12

Pi value is 3.14159

Example for Any

Topics 'solid physics', Hertz

کلام آخر

در این آموزش با مباحث مفهوم Type Casting در Swift و حالت های آن آشنا شدیم. با استفاده از این مفهوم شما می توانید متغیری برای دریافت هر نوع مقداری تعریف کنید

به اشتراک بگذارید

Type Casting در Swift

دیدگاه کاربران

تعداد دیدگاه : 0

پی وی لرن – آموزش برنامه نویسی و طراحی وب سایت

دوره های آموزشی آکادمی پی وی لرن (پروژه محور و ویژه بازار کار)

جلسه ۳۰ : قالب بندی نوع در Swift

مقدمه

قالب بندی نوع در Swift

تعریف یک سلسله مراتب کلاس

بررسی نوع

نفوذپذیری

کلید واژه ی Any در Typecasting

کلمه کلیدی AnyObject

کلام آخر

لیست مطالب دوره

مطالب ویژه

دسته های اصلی

برگه ها

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