为FFStatusDisplay单例的状态显示方法添加Continuation Block

Got it, let's add that continuation block to your showStatus:Timeout:Controller: method step by step. Here's how you can modify your code to support a completion handler that runs after the status alert dismisses:

First, update the method signature to include an optional completion block parameter. We'll make it nullable so callers aren't forced to use it:

// In your FFStatusDisplay.h file
- (void)showStatus:(NSString *)message 
           Timeout:(float)timeout 
        Controller:(UIViewController *)controller
        Completion:(void (^_Nullable)(void))completion;

Then, modify the implementation to store and execute the block once the alert finishes dismissing. We'll also handle the case where an alert is already being displayed:

// In your FFStatusDisplay.m file
- (void)showStatus:(NSString *)message 
           Timeout:(float)timeout 
        Controller:(UIViewController *)controller
        Completion:(void (^_Nullable)(void))completion {
    if (![self isDisplaying]) {
        [self setIsDisplaying:YES];
        
        // Finish creating your UIAlertController (your existing code here)
        UIAlertController *statusAlert = [UIAlertController alertControllerWithTitle:nil
                                                                             message:message
                                                                      preferredStyle:UIAlertControllerStyleAlert];
        [self setStatusAlert:statusAlert];
        
        [controller presentViewController:statusAlert animated:YES completion:nil];
        
        // Schedule dismissal and completion block execution
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(timeout * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            [statusAlert dismissViewControllerAnimated:YES completion:^{
                [self setIsDisplaying:NO];
                [self setStatusAlert:nil];
                
                // Run the continuation block if it was provided
                if (completion) {
                    completion();
                }
            }];
        });
    } else {
        // Handle the case where an alert is already showing
        // For this example, we'll immediately run the completion block
        // (you could instead update the existing alert's message/timeout if needed)
        if (completion) {
            completion();
        }
    }
}

Key Details: #

• The completion block runs after the alert is fully dismissed, using the dismissal's own completion handler to ensure UI state is updated first.
• Making the block nullable means existing calls to the method won't break—callers can choose to add the continuation only when needed.
• The "already displaying" logic is flexible: you can adjust it to update the current alert instead of ignoring the request, based on your app's needs.

Example Usage: #

[[FFStatusDisplay sharedInstance] showStatus:@"Task finished successfully!"
                                    Timeout:2.5
                                 Controller:self
                               Completion:^{
                                   // This code executes right after the alert disappears
                                   NSLog(@"Continuing with next operation...");
                                   [self loadNextScreen];
                               }];

内容的提问来源于stack exchange，提问作者David U