iOS中块（Objective-C）和闭包（Swift）之间的区别

Question

在教程中，它写的功能都是相同的，甚至闭包更容易阻塞，它避免了块和内存管理的复杂性，我已经经历了很多教程，但除了这些我没有得到swift的“闭包”和Objective-C“阻止”。

Answer 1

Excerpt From: Apple Inc. “Using Swift with Cocoa and Objective-C.” iBooks:

“Swift closures and Objective-C blocks are compatible, so you can pass Swift closures to Objective-C methods that expect blocks. Swift closures and functions have the same type, so you can even pass the name of a Swift function.

Closures have similar capture semantics as blocks but differ in one key way: Variables are mutable rather than copied. In other words, the behavior of __block in Objective-C is the default behavior for variables in Swift.”

Answer 2

Slight differences. One was mentioned; variables are captured as variables, not as values. Which can be either useful or a trap. Importantly you can define a capture list in a Swift closure, so if you include self.property in the capture list, then the value of that property is captured, and not self. That also simplifies capturing weak variables.

Answer 3

To show an actual code example of the differences:

This does compile:

let x : @convention(swift) (inout Int) -> ()

This does not:

let y : @convention(block) (inout Int) -> ()

with the error (inout Int) -> () is not representable in Objective-C