Struct XCTNSPredicateExpectation

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pub struct XCTNSPredicateExpectation { /* private fields */ }

Expand description

Expectation subclass for waiting on a condition defined by an NSPredicate and an object.

When an instance of this class is used from Swift and is awaited using fulfillment(of:)rather than wait(for:),XCTest evaluates the associated predicate on the main actor.

Implementations§

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pub unsafe fn initWithDescription( this: Allocated<Self>, expectation_description: &NSString, ) -> Retained<Self>

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pub unsafe fn initWithPredicate_object( this: Allocated<Self>, predicate: &NSPredicate, object: Option<&AnyObject>, ) -> Retained<Self>

Initializes an expectation that waits for a predicate to evaluate as true with the provided object.

When an instance of this class is used from Swift and is awaited using fulfillment(of:)rather than wait(for:),XCTest evaluates _predicate_on the main actor.

§Safety

object should be of the correct type.

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pub fn predicate(&self) -> Retained<NSPredicate>

Returns the predicate used by the expectation.

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pub fn object(&self) -> Option<Retained<AnyObject>>

Returns the object against which the predicate is evaluated.

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pub unsafe fn handler(&self) -> XCPredicateExpectationHandler

Available on crate feature block2 only.

Allows the caller to install a special handler to do custom evaluation of predicate and its object.

§Safety

The returned block must be sendable.

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pub unsafe fn setHandler(&self, handler: XCPredicateExpectationHandler)

Available on crate feature block2 only.

Setter for handler.

This is copied when set.

§Safety

handler must be a valid pointer or null.

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pub unsafe fn expectedFulfillmentCount(&self) -> NSUInteger

Unavailable on this class; XCTNSPredicateExpectation repeatedly evaluates its predicate until it becomes true. Once the predicate has become true, it is expected to remain true and will not be evaluated again. Setting expectedFulfillmentCount has no impact on fulfillment of the expectation.

This property is not atomic.

§Safety

This might not be thread-safe.

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pub unsafe fn setExpectedFulfillmentCount( &self, expected_fulfillment_count: NSUInteger, )

Setter for expectedFulfillmentCount.

§Safety

This might not be thread-safe.

Methods from Deref<Target = XCTestExpectation>§

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pub fn expectationDescription(&self) -> Retained<NSString>

The human readable string used to describe the expectation in log output and test reports.

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pub fn setExpectationDescription(&self, expectation_description: &NSString)

Setter for expectationDescription.

This is copied when set.

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pub fn isInverted(&self) -> bool

If an expectation is set to have inverted behavior, then fulfilling it will have a similar effect that failing to fulfill a conventional expectation has, as handled by the waiter and its delegate. Furthermore, waiters that wait on an inverted expectation will allow the full timeout to elapse and not report timeout to the delegate if it is not fulfilled.

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pub fn setInverted(&self, inverted: bool)

Setter for isInverted.

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pub unsafe fn expectedFulfillmentCount(&self) -> NSUInteger

The expectedFulfillmentCount is the number of times -fulfill must be called on the expectation in order for it to report complete fulfillment to its waiter. By default, expectations have an expectedFufillmentCount of 1. This value must be greater than 0 and is not meaningful if combined with @ inverted.

This property is not atomic.

§Safety

This might not be thread-safe.

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pub unsafe fn setExpectedFulfillmentCount( &self, expected_fulfillment_count: NSUInteger, )

Setter for expectedFulfillmentCount.

§Safety

This might not be thread-safe.

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pub unsafe fn assertForOverFulfill(&self) -> bool

If set, calls to fulfill() after the expectation has already been fulfilled - exceeding the fulfillment count - will raise. This is the legacy behavior of expectations created through APIs on XCTestCase but is not enabled for expectations created using XCTestExpectation initializers.

This property is not atomic.

§Safety

This might not be thread-safe.

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pub unsafe fn setAssertForOverFulfill(&self, assert_for_over_fulfill: bool)

Setter for assertForOverFulfill.

§Safety

This might not be thread-safe.

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pub fn fulfill(&self)

Call -fulfill to mark an expectation as having been met. It’s an error to call -fulfill on an expectation more times than its expectedFulfillmentCount value specifies, or when the test case that vended the expectation has already completed. If assertForOverFulfill is set when either of these occur, -fulfill will raise an exception.

Methods from Deref<Target = NSObject>§

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

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>§

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

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());

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

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

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.

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

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`
    }
}