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The ownership in iOS
Mixleap #11 in Osaka
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@_natpenguin
merpay
iOS Software Engineer
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@_natpenguin
merpay
iOS Software Engineer
.filter { $0 == } .map { $0 + } + [ , ✨ ]
=
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What is ownership?
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It’s a management system for resource
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It’s abstract word…
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Ownership system is already used
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Rust/C++/Swift…
Ownership system is already used
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Why we need ownership system?
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No content
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- Speed
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- Safety
- Speed
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- Safety
- Speed
- Concurrency
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Safety
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- Access conflict to Data
Rust prevents these in compiling
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- Access conflict to Data
Rust prevents these in compiling
- Using after releasing resource
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fn main() {
let x = vec![1, 2, 3];
let y = x;
println!(“x[0] is {}", x[0]);
}
This code will be compiling error
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fn main() {
let x = vec![1, 2, 3];
take(x);
println!(“x[0] is {}", x[0]);
}
fn take(v: Vec) {
// do something
}
This code will be compiling error
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fn main() {
let mut x = &100;
let mut y = &mut x;
*y += 1;
println!(“y is {}", y);
}
This code will be compiling error
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It’s a difficult
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No content
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Manifesto
https://github.com/apple/swift/blob/master/docs/OwnershipManifesto.md
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Q. What does swift want by using it?
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A. Improving performance
Q. What does swift want by using it?
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- Making extra copies at runtime
Problem Point
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- Making extra copies at runtime
- Referencing to unique resource
Problem Point
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- Making extra copies at runtime
- Referencing to unique resource
- Overhead of reference count
Problem Point
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Point
- Prevents simultaneously accessing to Data
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Point
- Prevents simultaneously accessing to Data
- Give programmers more control
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Point
- Prevents simultaneously accessing to Data
- Give programmers more control
- Add types that can’t be implicitly copied
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A1. Supporting a type that can’t copy
Q. How does swift improve performance?
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A1. Supporting a type that can’t copy
Q. How does swift improve performance?
A2. Law of exclusivity
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New keywords
- shared
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func ==(left: shared String, right: shared String) -> Bool {
...
}
shared
String isn’t copied
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What is different with inout?
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- shared
- inout
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New keywords
- shared
- moveonly
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moveonly struct Foo {
// some parameters
}
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moveonly extension Foo {
// Some extensions
}
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extension Foo {
moveonly func bar(_ u: U)
}
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moveonly struct File {
let descriptor: Int32
init(filename: String) throws {
descriptor = Darwin.open(filename, O_RDONLY)
}
deinit {
_ = Darwin.close(descriptor)
}
}
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When we use it?
- Performance tuning
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When we use it?
- More memory management
- Performance tuning
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When we use it?
- More memory management
- Performance tuning
- Already know that no needed to copy
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Thank you so much!