Solution to IOS nsnotification keyboard occlusion

Time:2021-10-21

Solution to IOS nsnotification keyboard occlusion

Get keyboard size from keyboard notification

The keyboard size exists in the nsnotification.

1; Add the keyboarddidshow and keyboarddidhide methods in adddrinkviewcontroller

2; Register uikeyboarddidshownotification and uikeyboarddidhidenotification in viewwillappear.

3; Unregister subscriptions to all events in viewwilldisappear

4; Add a bool member in adddrinkviewcontroller to track whether the keyboard is visible.

//
// ViewController.h
// scrol
//
// Created by gao wuhang on 12-12-5.
//Copyright (c) Gao Wuhang. All rights reserved
//

#import

@interface ViewController : UIViewController{
  BOOL keyboardVisible;
  UIScrollView *scrollView;
}

- (void)keyboardDidShow: (NSNotification*) notif;
- (void)keyboardDidHide: (NSNotification*) notif;

@property (nonatomic, retain) UIScrollView *scrollView;
@end

 
//
// ViewController.m
// scrol
//
// Created by gao wuhang on 12-12-5.
//Copyright (c) Gao Wuhang. All rights reserved
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

@synthesize scrollView;

- (void)viewWillAppear:(BOOL)animated{
  [super viewWillAppear:animated];
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidShow:) name:UIKeyboardDidShowNotification object:nil];
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidHide:) name:UIKeyboardDidHideNotification object:nil];
}

- (void)viewWillDisappear:(BOOL)animated{
  [[NSNotificationCenter defaultCenter] removeObserver:self];
}

- (void) keyboardDidShow:(NSNotification *)notif {
NSLog(@"%@", @"Received UIKeyboardDidShowNotification");
 
if (keyboardVisible) {
NSLog(@"%@", @"Keyboard is already visible. Ignoring notifications.");
return;
}
 
// The keyboard wasn't visible before
NSLog(@"Resizing smaller for keyboard");
 
// Get the origin of the keyboard when it finishes animating
NSDictionary *info = [notif userInfo];
NSValue *aValue = [info objectForKey:UIKeyboardFrameEndUserInfoKey];
 
// Get the top of the keyboard in view's coordinate system.
// We need to set the bottom of the scrollview to line up with it
CGRect keyboardRect = [aValue CGRectValue];
  keyboardRect = [self.view convertRect:keyboardRect fromView:nil];
CGFloat keyboardTop = keyboardRect.origin.y;
  
// Resize the scroll view to make room for the keyboard
  CGRect viewFrame = self.view.bounds;
viewFrame.size.height = keyboardTop - self.view.bounds.origin.y;
 
self.scrollView.frame = viewFrame;
keyboardVisible = YES;
}

- (void) keyboardDidHide:(NSNotification *)notif {
NSLog(@"%@", @"Received UIKeyboardDidHideNotification");
 
if (!keyboardVisible) {
NSLog(@"%@", @"Keyboard already hidden. Ignoring notification.");
return;
}
 
// The keyboard was visible
NSLog(@"%@", @"Resizing bigger with no keyboard");
  
// Resize the scroll view back to the full size of our view
self.scrollView.frame = self.view.bounds;
keyboardVisible = NO;
}

- (void)viewDidLoad
{
  scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, 320, 460)];
//  scroll.contentSize = CGSizeMake(1000, 1000);
  [self.view addSubview:scrollView];
//  UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(100, 100, 100, 100)];
//  [button setBackgroundColor:[UIColor blackColor]];
//  [scroll addSubview:button];
  UITextView *textView = [[UITextView alloc]initWithFrame:CGRectMake(100, 300, 100, 100)];
  textView.text = @"222";
  textView.font = [UIFont systemFontOfSize:20];
  [scrollView addSubview:textView];
  [super viewDidLoad];
  [textView release];

  self.scrollView.contentSize = self.view.frame.size;
// Do any additional setup after loading the view, typically from a nib.
}

- (void)dealloc
{
  [scrollView release];
  [super dealloc];
}

- (void)didReceiveMemoryWarning
{
  [super didReceiveMemoryWarning];
  // Dispose of any resources that can be recreated.
}

@end

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