Swift Strings
Swift 4 strings are ordered collection of characters, such as “Hello, World!” and they are represented by the Swift 4 data type String, which in turn represents a collection of values of Character type.
How to create a string?
A string can be created by using a string literal or creating an instance of a String class.
See this example:
Output:
Hello world! This is tutoraspire This is an example of multiple line string by tutoraspire
Empty Strings
To create empty string, you can use an empty string literal or create an instance of string class.
To check whether the string is empty or not, you can use the Boolean property isEmpty.
Example:
Output:
stringA is empty stringB is empty
Operations on Strings
We can operate a lot of operations on Swift strings.
String Concatenation
The + operator is used to concatenate two strings or a string and a character, or two characters in Swift.
Example:
Output:
Hello tutoraspire
String Interpolation
String interpolation is used to construct a new string value by mixing the values of constants, variables, literals, and expressions and include them inside a string literal. The values of variables and constants which you insert into string literal is wrapped in a pair of parentheses, prefixed by a backslash.
Example:
Output:
10 times 1000 is equal to 10000.0
String Length
String 4 doesn’t support length property, but we can use a global count() function to count the number of characters in a string.
Example:
Output:
Hello tutoraspire, string length is 16
String Comparison
The == operator is used to compare two strings variables or constants.
Example:
Output:
Hello, tutoraspire and Hello, World! are not equal
String Iteration
In Swift 4, strings are the collection of values, so we can iterate over strings using loops:
Example:
Output:
W e l c o m e t o J a v a T p o i n t
Iteration of Unicode Strings
We can access the UTF-8 and UTF-16 representation of the Unicode strings over its utf8 and utf16 properties.
Example:
Output:
UTF-8 Codes: 74 97 118 97 84 112 111 105 110 116 UTF-16 Codes: 74 97 118 97 84 112 111 105 110 116
Swift 4 String Functions and Operators
A list of functions and operators related to String in Swift 4:
| Index | Functions/Operators | Usage |
|---|---|---|
| 1) | isEmpty | It is used to check whether a string is empty or not. It specifies a Boolean value. |
| 2) | hasPrefix(prefix: String) | It is a function to check whether a given parameter string exists as a prefix of the string or not. |
| 3) | hasSuffix(suffix: String) | It is a function to check whether a given parameter string exists as a suffix of the string or not. |
| 4) | toInt() | It is a function to convert numeric String value into Integer. |
| 5) | count() | It is a global function to count the number of Characters in a string. |
| 6) | utf8 | It specifies a property to return a UTF-8 representation of a string. |
| 7) | utf16 | It specifies a property to return a UTF-16 representation of a string. |
| 8) | unicodeScalars | It specifies a property to return a Unicode Scalar representation of a string. |
| 9) | + | It is an operator to concatenate two strings, or a string and a character, or two characters. |
| 10) | += | It is an operator to append a string or character to an existing string. |
| 11) | == | It is an operator to determine the equality of two strings. |
| 12) | < | It is an operator to perform a lexicographical comparison to determine whether one string evaluates as less than another. |
| 13) | startIndex | It is used to get the value at starting index of string. |
| 14) | endIndex | It is used to get the value at ending index of string. |
| 15) | Indices | It is used to access the indices one by one. i.e. all the characters of string one by one. |
| 16) | insert(“Value”, at: position) | It is used to insert a value at a position. |
| 17) | remove(at: position) removeSubrange(range) | It is used to remove a value at a position, or to remove a range of values from string. |
| 18) | reversed() | It is used to return the reverse of a string. |