IOS is similar to the drop-down header view of the QQ space table view to enlarge the effect. ios View

IOS is similar to the drop-down header view of the QQ space table view to enlarge the effect. ios View

UITableView is a subclass of UIScrollView.
Therefore, the UIScrollView proxy method can also be applied on UITableView.
In this case, we can understand that in the drop-down process of the table, we need to make the image in the header appear slightly magnified. We can listen to events in a rolling view based on the scrolling view, you can change the size of the image by obtaining the amount of stretch from the drop-down list!

Therefore:

/*** Key processing: get the scroll offset from the scroll view to change the image changes */

The following code implements the effect:

@ Interface ViewController () <UITableViewDataSource, UITableViewDelegate> @ property (nonatomic, strong) UIImageView * headImageView; // header image @ property (nonatomic, strong) UITableView * tableView; // list @ property (nonatomic, strong) NSMutableArray * infoArray; // data source array @ end // screen width, high macro definition # define IPHONE_W ([UIScreen mainScreen]. bounds. size. width) # define IPHONE_H ([UIScreen mainScreen]. bounds. size. height) @ implementation ViewCont Rollerstatic CGFloat kImageOriginHight = 300;-(void) viewDidLoad {[super viewDidLoad]; // Add the view to the interface [self. view addSubview: self. tableView]; [self. tableView addSubview: self. headImageView] ;}# pragma mark -- proxy method of the rolling view-(void) scrollViewDidScroll :( UIScrollView *) scrollView {/*** key processing: get the scroll offset from the scroll view to change the image * // get the offset CGFloat yOffset = scrollView of the y value of the scroll view. contentOffset. y; NSLog (@ "yOffset = % f", yOffset); CGF Loat xOffset = (yOffset + kImageOriginHight)/2; if (yOffset <-kImageOriginHight) {CGRect f = self. headImageView. frame; f. origin. y = yOffset; f. size. height =-yOffset; f. origin. x = xOffset; // int abs (int I); // process the absolute value of the int type // double fabs (double I ); // process the absolute value of the double type // float fabsf (float I); // process the absolute value of the float type f. size. width = IPHONE_W + fabs (xOffset) * 2; self. headImageView. frame = f ;}# pragma mark -- table view proxy-(C GFloat) tableView :( UITableView *) tableView heightForRowAtIndexPath :( NSIndexPath *) indexPath {return 44;}-(NSInteger) tableView :( UITableView *) tableView numberOfRowsInSection :( NSInteger) section {return self. infoArray. count;}-(UITableViewCell *) tableView :( UITableView *) tableView cellForRowAtIndexPath :( NSIndexPath *) indexPath {static NSString * identify = @ "MyCellIndifer"; UITableViewCell * cell = [tableView de QueueReusableCellWithIdentifier: identify]; if (! Cell) {cell = [[UITableViewCell alloc] initWithStyle: UITableViewCellStyleDefault reuseIdentifier: identify];} cell. textLabel. text = [self. infoArray objectAtIndex: indexPath. row]; return cell ;}# pragma mark -- get initialization operation-(UITableView *) tableView {if (_ tableView = nil) {_ tableView = [[UITableView alloc] initWithFrame: CGRectMake (0, 0, IPHONE_W, IPHONE_H)]; _ tableView. delegate = self; _ tableView. dataSource = self; _ TableView. backgroundColor = [UIColor lightGrayColor]; // The content is displayed at kImageOriginHight. _ TableView. contentInset = UIEdgeInsetsMake (kImageOriginHight, 0, 0);} return _ tableView;}-(NSMutableArray *) infoArray {if (_ infoArray = nil) {_ infoArray = [[NSMutableArray alloc] init]; for (int I = 0; I <40; I ++) {[_ infoArray addObject: @ "this is a test! "] ;}} Return _ infoArray;}-(UIImageView *) headImageView {if (_ headImageView = nil) {_ headImageView = [[UIImageView alloc] initWithImage: [UIImage imageNamed: @ "111"]; _ headImageView. frame = CGRectMake (0,-kImageOriginHight, IPHONE_W, kImageOriginHight);} return _ headImageView ;}

Display:

About:
For details about how to set and use the scrolling views contentSize, contentOffset, and contentInset, you can view the scrolling views contentSize, contentOffset, and contentInset.

Demo download: Click here to download the demo.

Copyright Disclaimer: This article is an original article by the blogger and cannot be reproduced without the permission of the blogger.