Correcting A Sticky Header Class and Port to Swift

Job Description: This job require a familiar experience in customizing Flow Layout of IOS application. Currently the class already working producing output based on the attached file. Developer need to solve the glitch and rewrite the class to Swift with proper indentation and comments. Problem Scenario: The section header have been properly overlay the cell item, to create a frosted effect of the cell item (this effect not require in this job) using live blur. But the layout failed to properly calculate the location of the items and header thus introducing another glitch whereby there's a gap between section header no#3 and no#4 and it will be snap back to lower bottom of header no#3 after another slide up. Please refer the both screenshot.