这是一个创建于 1585 天前的主题，其中的信息可能已经有所发展或是发生改变。
struct MyView: View {
@Binding var a: Bool
init(a: Binding<Bool> = .constant(true)) {
_a = a
}
var body: some View {
Text("MyView")
}
}
这里面的_a中的_是什么作用，我在文档上没有找到
第 1 条附言 · 2020-07-31 15:55:48 +08:00
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Procumbens 2020-07-30 07:45:07 +08:00
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ufo22940268 OP @Procumbens 好像是两个事情，你看我的 snippet 里面定义的变量名是没有_开头的，但是赋值的时候就加上了_
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Nitroethane 2020-07-30 08:08:32 +08:00  1
In Objective-C when you declare a property @synthesize would create the getter and setters for you automatically since clang 3.2. So, the default @synthesize for a property "foo" would look like this:
@synthesize foo = _foo because of that _foo would then be the iVar. In other words you could have done the @synthesize yourself and called the iVar whatever you liked: @synthesize foo = myiVarFoo so in this case there is no "_" So now in Swift from the documentation: Swift unifies these concepts into a single property declaration. A Swift property does not have a corresponding instance variable, and the backing store for a property is not accessed directly. So from the documentation it's clear that swift does not have a corresponding instance variable thus no need to have the "_" around anymore. https://stackoverflow.com/a/24215607 |
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