Author: saqibkhan

Swift Operator Precedence

Operator precedence determines evaluation order.

Multiplication comes before addition; && before ||.

Use parentheses to control order.

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Control order of evaluation with precedence

Understand how operators are prioritized and add parentheses to make evaluation order explicit when needed.

Example

print(2 + 3 * 4)
print((2 + 3) * 4)
print(true || false && false)
print((true || false) && false)

This example shows how parentheses change the result.

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Boolean Precedence

&& is evaluated before ||. Use parentheses to clarify intention.

Example

let a = true
let b = false
let c = true

print(a || b && c)         // true (&& before ||)
print((a || b) && c)       // true
print(a && b || c)         // true ((a && b) || c)

Swift Logical Operators

Combine booleans with && (AND), || (OR), and ! (NOT).

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Logical AND (&&)

Both must be true for the result to be true.

Example

let isOwner = true
let isAdmin = false
print(isOwner && isAdmin)
print(true && true)

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Logical OR (||)

At least one true makes the result true.

Example

let a = true
let b = false
print(a || b)
print(false || false)

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Logical NOT (!)

Flip a boolean value: true becomes false and vice versa.

Example

let flag = false
print(!flag)
print(!true)

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Swift Comparison Operators

Use comparison operators to compare values: ==, !=, >, <, >=, <=.

They return Bool.

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Compare Integers

Use ==, !=, >, <, >=, and <= to compare numeric values.

The result is a Bool.

Example

let a = 5, b = 2
print(a == b)
print(a != b)
print(a > b)
print(a < b)
print(a >= 5)

This example prints the result of several comparisons.

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Compare Strings

Strings compare lexicographically (dictionary order).

Comparison is case-sensitive.

Example

print("apple" < "banana")  // true
print("Swift" == "Swift")  // true
print("cat" > "car")       // true

This example compares strings using the same operators.

Swift Assignment Operators

Use = to assign a value.

Compound assignment operators like +=, -=, *= and /= update a variable in place.

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Compound Assignment

Use compound operators like += and *= to update a variable in place.

Example

var total = 10
total += 5
print(total)
total -= 3
print(total)
total *= 2
print(total)
total /= 4
print(total)

This example shows updating a variable with compound assignment operators.

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Append to String

You can also use += with strings to append text to a mutable string variable.

Example

var s = "Hello"
s += ", Swift"
print(s)

This example appends to a string in place with +=.

Swift Arithmetic Operators

Use +, -, *, and / to add, subtract, multiply and divide.

Integer division truncates toward zero.

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Examples

These examples show addition, subtraction, multiplication and integer division.

Example

let a = 7, b = 3
print(a - b)
print(a * b)
print(a / b)        // integer division

This example demonstrates arithmetic with integers.

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Remainder Operator

The remainder operator % gives the leftover after integer division.

Example

print(7 % 3)   // 1
print(8 % 2)   // 0
print(10 % 6)  // 4

Use % to check divisibility or cycle through a fixed range.

Swift Operators

Operators perform operations on values.

Common groups are arithmetic, assignment, comparison and logical operators.

Swift also has well-defined precedence.

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Operator families at a glance

Explore arithmetic, assignment, comparison, and logical operators, and how precedence affects evaluation order.

Example

let a = 5, b = 2
// Arithmetic
print(a + b)
// Comparison
print(a > b)
// Logical
let t = true, f = false
print(t && !f)

This example shows arithmetic (+), comparison (>) and logical (&&, !) operators.

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Unary and Ternary

Unary operators act on a single operand (like ! to negate a boolean).

The ternary conditional operator condition ? a : b chooses between two values.

Example

let flag = false
print(!flag)              // unary NOT
let score = 85
let label = (score >= 90) ? "A" : "Not A"
print(label)

This example flips a boolean with unary ! and uses the ternary operator to pick a string based on a condition.

Swift Type Casting

Use as, as?, and as! to convert between types, especially with protocols and Any.

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Upcasting and Downcasting

Convert a value to a supertype (upcast) or attempt to convert back to a subtype using optional downcasting with as?.

Example

let items: [Any] = [1, "Swift"]
for item in items {
  if let i = item as? Int {
print("Int: \(i)")
  } else if let s = item as? String {
print("String: \(s)")
  }
}

This example conditionally casts values from Any to their concrete types.

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Forced Downcast

Use as! only when you are certain of the runtime type. If the cast fails, the program will crash.

Example

let value: Any = 42
let i = value as! Int   // forced downcast
print(i)

Prefer optional casting (as?) when the type may vary, and unwrap safely.

Swift Characters

Character is one user-visible character.

Strings are collections of characters.

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Characters and String Length

Use Character for single letters.

Use String.count to get the number of characters.

Example

let ch: Character = "A"
print(ch)
let word = "Swift"
print(word.count)

This prints a character and a string length.

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Characters and String Conversion

Convert between Character and String as needed.

Example

let ch: Character = "A"
let s = String(ch)
print(s)              // "A"

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Unicode and Grapheme Clusters

Some characters use multiple Unicode scalars but still count as one character.

Example

let heart: Character = "❤️"
print(heart)
let flag: Character = "🇳🇴" // composed of two regional indicators
print(flag)
print("e\u{301}".count) // 1 (e + combining acute accent)

Swift Booleans

Bool represents logical true/false. Combine conditions with &&, ||, and negate with !.

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Boolean Logic

Combine boolean values using logical AND (&&), OR (||), and negate with NOT (!).

Example

let a = true, b = false
print(a && b)
print(a || b)
print(!a)

This example shows logical AND, OR and NOT.

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Comparison Results

Relational operators like >, ==, and != return Bool values that you can use in conditions.

Example

let a = 5, b = 3
print(a > b)   // true
print(a == b)  // false
print(a != b)  // true

Comparisons like >, ==, and != produce Bool values you can combine with logical operators.

Swift Numbers

Swift has integer types (like Int) and floating-point types (like Double).

Use arithmetic operators to add, subtract, multiply and divide numbers.

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Arithmetic

Use +, -, *, and / to perform numeric operations. Convert types when needed.

Example

let a = 5, b = 2
print(a - b)
print(a * b)
print(Double(a) / Double(b))

This example demonstrates basic arithmetic and integer-to-double conversion for division.

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Integer Division vs Remainder

Integer division drops any fractional part, while % returns the remainder.

Example

let a = 7, b = 3
print(a / b)  // 2 (integer division)
print(a % b)  // 1 (remainder)

This example shows how integer division truncates toward zero and how the remainder operator % returns the leftover.