How to accomplish a weak delegate，and the protocol in swift How to inherit ？
The way to accomplish a weak delegate，and that protocol‘s inheritance in swift ？
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A smaple:
protocol ProtocolNameDelegate { // Protocol stuff goes here } class SomeClass { weak var delegate: ProtocolNameDelegate? \\ error occured }-
error:
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当你在swift中为代理设置weak属性以便于避免循环引用的时候，报编译错误
'weak' may only be applied to class and class-bound protocol types, not 'MyImageCellDelegate'
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Why did this error occur?
- 因为在swift中协议是不仅可以被引用类型实现，也可以被值类型引用，但是weak只能用来修饰引用类型，所以在使用weak修饰没有加任何限定词的协议时报错，我们将如何使用weak修饰协议定义的类型属性呢
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有如下三种方法：
protocol ProtocolNameDelegate: class { // Protocol stuff goes here } or protocol ProtocolNameDelegate: NSObjectProtocol { // Protocol stuff goes here } or @objc protocol ProtocolNameDelegate { // Protocol stuff goes here } Although, under code is successed to build, but which one is the best? class SomeClass { weak var delegate: ProtocolNameDelegate? } -
which one is the best way to use the weak keywords with Protocol Type Parameter ?
- NSObjectProtocol is equal to NSObject Protrocol in Objective-C
- @objc keyword is define the type as objective-c types
- class keyword limit the protocol only used for reference type in swift
All in all ， NSObjectProtocol > class > @objc
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- 因为在swift中协议是不仅可以被引用类型实现，也可以被值类型引用，但是weak只能用来修饰引用类型，所以在使用weak修饰没有加任何限定词的协议时报错，我们将如何使用weak修饰协议定义的类型属性呢
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