The updateValue()
method updates the value in the dictionary for the given key.
Example
// create a dictionary with two elements
var information = ["Charlie": 54, "Harvey": 34]
// update value of "Charlie" to 57
information.updateValue(57, forKey: "Charlie")
// print updated dictionary
print(information)
// Output: ["Charlie": 57, "Harvey": 34]
updateValue() Syntax
The syntax of the updateValue()
method is:
dictionary.updateValue(new_value, forKey: key)
Here, dictionary is an object of the Dictionary
class.
updateValue() Parameters
The updateValue()
method takes one parameter:
new_value
- the new value to addkey
- the key whose value is to be updated.
Note: If the key doesn't already exist, the new key-value pair is created.
updateValue() Return Value
- The
updateValue()
method returns the value that was replaced.
Note: The method returns nil
if new key-value pair is added.
Example 1: Swift updateValue()
// create a dictionary with two elements
var marks = ["Sabby": 78, "Nick": 59]
print("Marks Before:", marks)
// update value of "Nick" to 67
marks.updateValue(67, forKey: "Nick")
// print updated dictionary
print("Marks After:", marks)
Output
Marks Before: ["Nick": 59, "Sabby": 78] Marks After: ["Nick": 67, "Sabby": 78]
Example 2: Create new key-value Pair
// create a dictionary with two elements
var marks = ["Sabby": 78, "Nick": 59]
print("Before:", marks)
// associate value 45 to new key Sazz
marks.updateValue(45,forKey: "Sazz")
// print updated dictionary
print("After:", marks)
Output
Before: ["Sabby": 78, "Nick": 59] After: ["Sabby": 78, "Nick": 59, "Sazz": 45]
Here, since there is no key named "Sazz"
in the marks dictionary, so the new key-value pair is created.