IOS NSNotification 键盘遮挡问题的解决办法

//// ViewController.h// scrol//// Created by gao wuhang on 12-12-5.// Copyright (c) 2012年 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) 2012年 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 beforeNSLog(@"Resizing smaller for keyboard"); // Get the origin of the keyboard when it finishes animatingNSDictionary *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 itCGRect 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 visibleNSLog(@"%@", @"Resizing bigger with no keyboard");  // Resize the scroll view back to the full size of our viewself.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