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Is there a way to capture multiple arguments weakly in a swift closure? I know this is the syntax to capture one argument weakly:
{ [weak arg] arg.doSomething() } How can I do this for two objects that I wish to capture weakly?
924
A closure can capture constants and variables from the surrounding context in which it's defined. The closure can then refer to and modify the values of those constants and variables from within its body, even if the original scope that defined the constants and variables no longer exists.
In Swift, closures capture the variables they reference: variables declared outside of the closure but that you use inside the closure are retained by the closure by default, to ensure they are still alive when the closure is executed.
Closures in Swift are similar to blocks in C and Objective-C and to lambdas in other programming languages. Closures can capture and store references to any constants and variables from the context in which they're defined. This is known as closing over those constants and variables.
As shown in the above table, there are three types of closures in Swift, namely global functions, nested functions, and closure expressions. They differ in several aspects, including their use scopes, their names, and whether they capture values, which will be discussed more in a later section.
From Expressions in "The Swift Programming Language" (emphasis added):
Closure Expression
...
A closure expression can explicitly specify the values that it captures from the surrounding scope using a capture list. A capture list is written as a comma separated list surrounded by square brackets, before the list of parameters. If you use a capture list, you must also use theinkeyword, even if you omit the parameter names, parameter types, and return type.
Example:
{ [weak arg1, weak arg2] in // ... } If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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