Single and double quotes both work in Dart
final myString = 'hello';
is the same as
final myString = "hello";
Delimiters need to be escaped
Use a \ backslash to escape single quotes in a single quote string.
final myString = 'Bob\'s dog'; // Bob's dog
Same thing to escape double quotes in a double quote string.
final myString = "a \"quoted\" word"; // a "quoted" word
But no need to escape anything if the delimiter is different.
final myString = "Bob's dog"; // Bob's dog
final myString = 'a "quoted" word'; // a "quoted" word
Also no need to worry about the value passed into an interpolated string.
final value=""quoted""; // "quoted"
final myString = "a $value word"; // a "quoted" word
Prefer single quotes in Flutter
The Flutter style guide recommends using single quotes for everything
final myString = 'hello';
except for nested strings
print('Hello ${name.split(" ")[0]}');
or strings containing single quotes (optional)
final myString = "Bob's dog";
final myString = 'Bob\'s dog'; // ok
The Dart style guide appears to be silent on the issue.