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Create a CATextlayer that changes at intervals in AVMutableVideoComposition

I have an application that allows the user to record video in a mutable composition. I would like to set some kind of text that will appear and then change at the interval that I set when the user plays it after export.

For example, if the first word is “dog”, then I would like to configure it so that “cat” replaces this string X seconds later, and then is replaced by another word after X seconds.

My video is exported from AVMutableComposition using AVExportSession, and my words will be added using the CATextlayer added to it as follows:

//code to setup AVMutableComposition
...
//code to setup CATextLayer and AVMutableVideoComposition
    CALayer *animatedTitleLayer = [CALayer layer];
    CATextLayer *titleLayer = [[CATextLayer alloc] init];
    titleLayer.string = @"Text I want to change at an interval";
    titleLayer.alignmentMode = kCAAlignmentCenter;
    titleLayer.bounds = CGRectMake(150, 50, 124, 354);
    titleLayer.position = CGPointMake(120, 270);
    titleLayer.bounds = CGRectIntegral(CGRectMake(0, 0, 250, 150));
    titleLayer.opacity = 1;
    titleLayer.backgroundColor = [UIColor purpleColor].CGColor;   
    [animatedTitleLayer addSublayer:titleLayer];
    animatedTitleLayer.position = CGPointMake(40, 5);        
    CALayer *parentLayer = [CALayer layer];
    CALayer *videoLayer = [CALayer layer];
    parentLayer.frame = CGRectMake(0, 0, 320, 480);
    videoLayer.frame = CGRectMake(0, 0, 320, 480);
    [parentLayer addSublayer:videoLayer];
    [parentLayer addSublayer:animatedTitleLayer];   
    parentLayer.preferredTransform = rotationTransform;
    AVMutableVideoComposition *videoComposition;
    videoComposition = [AVMutableVideoComposition videoComposition];
    videoComposition.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];

//code to setup AVExportSession
...

My question is: how can I change the text at the interval that I set for the lines that I designated?

.

+5
1

, , CATextLayer , - - . , , .

:

CALayer name.

, , name CATextLayer. titleLayer:

titleLayer.name = "changingTextLayer"

:

for (CALayer *layer in [superLayerOfMyLayer sublayers]) {
        if ([[layer name] isEqualToString:"changingTextLayer"]) {
            return layer;
        }
    }

, :

titleLayer.string = @"Changed text";

, , / , .

CALayer CATextLayer.

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