Comments[edit]
Humans use comments to document code for other humans. They have no effect on the program's operation itself.
Single-line comments[edit]
Multi-line comments[edit]
Output[edit]
print[edit]
print with separator[edit]
print with terminator[edit]
Types[edit]
In Swift, it is customary to capitalize all types.
- Int
- A signed integer value type
- Float
- A single-precision, floating-point value type
- Double
- A double-precision, floating-point value type
- String
- A Unicode string value that is a collection of characters
Constant and Variable Declarations[edit]
Constant declarations[edit]
Constants (named values that should never change) use the let keyword.
Variable Declarations[edit]
Variables (named values that could change) use the var keyword.
Control Structures[edit]
Control structures are used to alter the otherwise sequential flow of a program.
Conditionals[edit]
Conditionals are used to execute a segment of code if a condition is met.
if[edit]
else[edit]
if n < 10 {
print("n is less than 10")
} else {
print("n is not less than 10")
}
switch[edit]
switch n {
case 0:
print("n is zero")
case 1:
print("n is one")
default:
print("n is neither one nor zero")
}
Loops[edit]
Loops are used to repeat a segment of code until a condition is met.
for[edit]
The for loop is helpful when the number of iterations is known.
// From zero up to but excluding ten
for n in 0 ..< 10 {
print(n)
}
// From one up to and including 10
for n in 1 ... 10 {
print(n)
}
while[edit]
The while loop is helpful when the condition might initially be false and the statements should not be executed.
while n < 10 {
n += 1
}
repeat while[edit]
The repeat while loop is helpful when the statements should be executed at least once.
repeat {
n += 1
} while n < 10
