Executor performing blocks at least after 0.2 sec since last scrolling

WhenNoScrollingExecutor.m

static NSTimeInterval const kMinInactiveTime = 0.2;

//

@interface WhenNoScrollingExecutor : NSObject

@property (assign, nonatomic) BOOL runLoopModeWasUITrackingAgain;

- (void)executeBlock:(void (^)())block;
- (void)executeBlock:(void (^)())block completion:(void (^_Nullable)())completion;

@end

@implementation WhenNoScrollingExecutor

- (instancetype)init {
    self = [super init];
    if (self) {
        [self tick];
    }
    return self;
}

- (void)tick {
    if ([[NSRunLoop mainRunLoop] respondsToSelector:@selector(performInModes:block:)]) {
        @weakify(self);
        [[NSRunLoop mainRunLoop] performInModes:@[ UITrackingRunLoopMode ] block:^{
            @strongify(self);
            [self tock];
        }];
    }
    else {
        [[NSRunLoop mainRunLoop] performSelector:@selector(tock) target:self argument:nil order:0 modes:@[ UITrackingRunLoopMode ]];
    }
}

- (void)tock {
    self.runLoopModeWasUITrackingAgain = YES;
    if ([[NSRunLoop mainRunLoop] respondsToSelector:@selector(performInModes:block:)]) {
        @weakify(self);
        [[NSRunLoop mainRunLoop] performInModes:@[ NSDefaultRunLoopMode ] block:^{
            @strongify(self);
            [self tick];
        }];
    }
    else {
        [[NSRunLoop mainRunLoop] performSelector:@selector(tick) target:self argument:nil order:0 modes:@[ NSDefaultRunLoopMode ]];
    }
}

- (void)executeBlock:(void (^)())block {
    [self executeBlock:block completion:nil];
}

- (void)executeBlock:(void (^)())block completion:(void (^_Nullable)())completion {
    [self executeBlock:block completion:completion forceWait:NO];
}

- (void)executeBlock:(void (^)())block completion:(void (^_Nullable)())completion forceWait:(BOOL)forceWait {
    if (!forceWait && [[NSRunLoop mainRunLoop].currentMode isEqualToString:NSDefaultRunLoopMode]) {
        block();
        if (completion) {
            completion();
        }
        return;
    }

    if ([[NSRunLoop mainRunLoop] respondsToSelector:@selector(performInModes:block:)]) {
        @weakify(self);
        [[NSRunLoop mainRunLoop] performInModes:@[ NSDefaultRunLoopMode ] block:^{
            @strongify(self);
            [self executeBlockWhenNoScrolling:block];
        }];
    }
    else {
        [[NSRunLoop mainRunLoop] performSelector:@selector(executeBlockWhenNoScrolling:) target:self argument:block order:0 modes:@[ NSDefaultRunLoopMode ]]
    }
}

- (void)executeBlockWhenNoScrolling:(void (^)())block {
    self.runLoopModeWasUITrackingAgain = NO;
    @weakify(self);
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(kMinInactiveTime * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        @strongify(self);
        [self executeBlock:block forceWait:self.runLoopModeWasUITrackingAgain];
    });
}

@end