Struct UIFocusDebugger

Source

#[repr(C)]
pub struct UIFocusDebugger { /* private fields */ }

Available on crate feature UIFocusDebugger only.

Expand description

UIFocusDebugger provides a collection of runtime utilities for debugging issues related to focus interaction.

Implementations§

Source §

impl UIFocusDebugger

Source

pub unsafe fn help( mtm: MainThreadMarker, ) -> Retained<ProtocolObject<dyn UIFocusDebuggerOutput>>

Outputs an overview of all supported debugging utilities and other relevant information.

To use in Swift, enter po UIFocusDebugger.help() when paused in lldb.
To use in Objective-C, enter po [UIFocusDebugger help] when paused in lldb.

Source

pub unsafe fn status( mtm: MainThreadMarker, ) -> Retained<ProtocolObject<dyn UIFocusDebuggerOutput>>

Outputs information for the currently focused item.

To use in Swift, enter po UIFocusDebugger.status() when paused in lldb.
To use in Objective-C, enter po [UIFocusDebugger status] when paused in lldb.

Source

pub unsafe fn checkFocusabilityForItem( item: &ProtocolObject<dyn UIFocusItem>, ) -> Retained<ProtocolObject<dyn UIFocusDebuggerOutput>>

Available on crate feature UIFocus only.

Outputs a diagnosis of the specified item’s focusability, including any known issues that may be preventing focusability.

To use in Swift, enter po UIFocusDebugger.checkFocusability(for: <item reference>) when paused in lldb.
To use in Objective-C, enter po [UIFocusDebugger checkFocusabilityForItem: <item reference>] when paused in lldb.

Source

pub unsafe fn simulateFocusUpdateRequestFromEnvironment( environment: &ProtocolObject<dyn UIFocusEnvironment>, ) -> Retained<ProtocolObject<dyn UIFocusDebuggerOutput>>

Available on crate feature UIFocus only.

Simulates a fake focus update requested by the specified environment (e.g. [focusSystem requestFocusUpdateToEnvironment:environment]), outlining each step of the process for determining the next focused item.

To use in Swift, enter po UIFocusDebugger.simulateFocusUpdateRequest(from: <environment reference>) when paused in lldb.
To use in Objective-C, enter po [UIFocusDebugger simulateFocusUpdateRequestFromEnvironment: <environment reference>] when paused in lldb.

Source

pub unsafe fn focusGroupsForEnvironment( environment: &ProtocolObject<dyn UIFocusEnvironment>, ) -> Retained<ProtocolObject<dyn UIFocusDebuggerOutput>>

Available on crate feature UIFocus only.

Outputs a diagnosis of the focus groups of the specified environment and its children. Pass a focus system as the environment to get the full focus group tree for this focus system.

To use in Swift, enter po UIFocusDebugger.focusGroups(for: <environment reference>) when paused in lldb.
To use in Objective-C, enter po [UIFocusDebugger focusGroupsForEnvironment: <environment reference>] when paused in lldb.

Source

pub unsafe fn preferredFocusEnvironmentsForEnvironment( environment: &ProtocolObject<dyn UIFocusEnvironment>, ) -> Retained<ProtocolObject<dyn UIFocusDebuggerOutput>>

Available on crate feature UIFocus only.

Outputs a diagnoses of the preferred focus environments tree.

To use in Swift, enter po UIFocusDebugger.preferredFocusEnvironments(for: <environment reference>) when paused in lldb.
To use in Objective-C, enter po [UIFocusDebugger preferredFocusEnvironmentsForEnvironment: <environment reference>] when paused in lldb.

Source §

impl UIFocusDebugger

Methods declared on superclass NSObject.

Source

pub unsafe fn init(this: Allocated<Self>) -> Retained<Self>

Source

pub unsafe fn new(mtm: MainThreadMarker) -> Retained<Self>

Methods from Deref<Target = NSObject>§

Source

pub fn doesNotRecognizeSelector(&self, sel: Sel) -> !

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>§

Source

pub fn class(&self) -> &'static AnyClass

Available on crate feature UIIndirectScribbleInteraction only.

Dynamically find the class of this object.

§Panics

May panic if the object is invalid (which may be the case for objects returned from unavailable init/new methods).

§Example

Check that an instance of NSObject has the precise class NSObject.

use objc2::ClassType;
use objc2::runtime::NSObject;

let obj = NSObject::new();
assert_eq!(obj.class(), NSObject::class());

Source

pub unsafe fn get_ivar<T>(&self, name: &str) -> &T
where T: Encode,

👎Deprecated: this is difficult to use correctly, use Ivar::load instead.

Available on crate feature UIIndirectScribbleInteraction only.

Use Ivar::load instead.

§Safety

The object must have an instance variable with the given name, and it must be of type T.

See Ivar::load_ptr for details surrounding this.

Source

pub fn downcast_ref<T>(&self) -> Option<&T>
where T: DowncastTarget,

Available on crate feature UIIndirectScribbleInteraction only.

Attempt to downcast the object to a class of type T.

This is the reference-variant. Use Retained::downcast if you want to convert a retained object to another type.

§Mutable classes

Some classes have immutable and mutable variants, such as NSString and NSMutableString.

When some Objective-C API signature says it gives you an immutable class, it generally expects you to not mutate that, even though it may technically be mutable “under the hood”.

So using this method to convert a NSString to a NSMutableString, while not unsound, is generally frowned upon unless you created the string yourself, or the API explicitly documents the string to be mutable.

See Apple’s documentation on mutability and on isKindOfClass: for more details.

§Generic classes

Objective-C generics are called “lightweight generics”, and that’s because they aren’t exposed in the runtime. This makes it impossible to safely downcast to generic collections, so this is disallowed by this method.

You can, however, safely downcast to generic collections where all the type-parameters are AnyObject.

§Panics

This works internally by calling isKindOfClass:. That means that the object must have the instance method of that name, and an exception will be thrown (if CoreFoundation is linked) or the process will abort if that is not the case. In the vast majority of cases, you don’t need to worry about this, since both root objects NSObject and NSProxy implement this method.

§Examples

Cast an NSString back and forth from NSObject.

use objc2::rc::Retained;
use objc2_foundation::{NSObject, NSString};

let obj: Retained<NSObject> = NSString::new().into_super();
let string = obj.downcast_ref::<NSString>().unwrap();
// Or with `downcast`, if we do not need the object afterwards
let string = obj.downcast::<NSString>().unwrap();

Try (and fail) to cast an NSObject to an NSString.

use objc2_foundation::{NSObject, NSString};

let obj = NSObject::new();
assert!(obj.downcast_ref::<NSString>().is_none());

Try to cast to an array of strings.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);
// This is invalid and doesn't type check.
let arr = arr.downcast_ref::<NSArray<NSString>>();

This fails to compile, since it would require enumerating over the array to ensure that each element is of the desired type, which is a performance pitfall.

Downcast when processing each element instead.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);

for elem in arr {
    if let Some(data) = elem.downcast_ref::<NSString>() {
        // handle `data`
    }
}