我们在TextField输入时经常会出现被虚拟键盘挡住的现象，下面是具体的解决办法

1. //要用到textfield的代理

2. @interface ScrollerViewController ()<UITextFieldDelegate> {

3.    BOOL keyboardIsShown;//键盘是否出现

4.    CGPoint offset;//记录在键盘出现前，scrollview的contentOffset

5. }

6. @property (nonatomic, retain) UIScrollView *scrollView;

7. @property (nonatomic, retain) UITextField *textField;

8. @end

首先设置scrollview和加载textField

1. - (void)viewDidLoad

2. {

3.    //设置ScrollView

4.    scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];

5.    self.scrollView.zoomScale = 1.0;

6.    self.scrollView.contentSize = CGSizeMake(320, 1128);

7.    self.scrollView.contentOffset = CGPointMake(0, 0);

8.    self.scrollView.bounces = NO;

9.    //设置显示textField

10. for (int i = 0; i < 10; i++) {

11.        UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(20, 20 + i * 38, 70, 30)];

12.        label.text  = [NSString stringWithFormat:@"label%i",i + 1];

13.        label.textAlignment = NSTextAlignmentCenter;

14.        label.backgroundColor = [UIColor clearColor];

15.        label.textColor = [UIColor whiteColor];

16.        textField = [[UITextField alloc] initWithFrame:CGRectMake(100, 20 + i * 38, 200, 30)];

17.        self.textField.backgroundColor = [UIColor whiteColor];

18.        self.textField.delegate = self;

19.        self.textField.borderStyle = UITextBorderStyleRoundedRect;

20.        [self.scrollView addSubview:label];

21.        [self.scrollView addSubview:self.textField];

22.        [label release];

23.        [self.textField release];

24.    }

25.    [self.view addSubview:self.scrollView];

26.    [super viewDidLoad];

27.    // Do any additional setup after loading the view, typically from a nib.

28. }

在View出现之前，注册两个通知。它能通知你什么时候keyboard出现或消失。

1. - (void)viewWillAppear:(BOOL)animated{

2.    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(keyboardDidShow:)

3. name:UIKeyboardDidShowNotification

4.                                                           object:self.view.window];

5.    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(keyboardDidHide:)

6. name:UIKeyboardDidHideNotification

7.                                                          object:nil];

8.    [super viewWillAppear:animated];

9. }

当任何textField被点击时textFieldDidBeginEditing:被激活，你可以保存一个正在被点击textField的拷贝。

1. - (void)textFieldDidBeginEditing:(UITextField *)textFieldView{

2.    textField = textFieldView;

3. }

当点击keyboard上的Return键时textFieldShouldReturn:方法会响应

1. - (BOOL)textFieldShouldReturn:(UITextField *)textFieldView{

2.    [textFieldView resignFirstResponder];

3. returnNO;

4. }

当keyboard隐藏，结束输入时textFieldDidEndEditing:方法会被textfield会被设为nil。

1. - (void)textFieldDidEndEditing:(UITextField *)textFieldView{

2.    textField = nil;

3. }

当键盘出现时，通过notification设置，keyboardDidShow:方法开始响应。方法中最重要的是获取键盘的高度，例如输入中文时，键盘会多出一行选字提示，高度就会发生变化，所以不能设成固定的216。然后重新设置ScrollView的frame，将textField滚动到可见位置。

如果键盘已经出现时，点击另一个textField，这个方法会自动退出。因为keyboardIsShown已经设为YES。如果点击的textField有部分隐藏，它会自动滚动到可见区域。

1. - (void)keyboardDidShow:(NSNotification *)notification{

2.    //当键盘已经出现

3.    if (keyboardIsShown) {

4. return;

5.    }

6.    NSDictionary *info = [notification userInfo];

7.    //获取keyboard的size

8.    NSValue *aValue = [info objectForKey:UIKeyboardFrameEndUserInfoKey];

9.    CGRect keyboardRect = [self.view convertRect:[aValue CGRectValue] fromView:nil];

10.    NSLog(@"%f", keyboardRect.size.height);

11.    //获取scrollView的contentOffset,当前的滚动位置

12.    offset = self.scrollView.contentOffset;

13.    //当键盘存在时,重新设置scrollView的size

14.    CGRect viewFrame = [self.scrollView frame];

15.    viewFrame.size.height -= keyboardRect.size.height;

16.    self.scrollView.frame = viewFrame;

17.    //将textField滚动到可见区域

18.    CGRect textFieldRect = [self.textField frame];

19.    [self.scrollView scrollRectToVisible:textFieldRect animated:YES];

20.    keyboardIsShown = YES;

21. }

当键盘消失时，keyboardDidHide:开始响应。还原ScrollView的frame

1. - (void)keyboardDidHide:(NSNotification *)notification{

2.    //获取键盘size

3.    NSDictionary* info = [notification userInfo];

4.    NSValue* aValue = [info objectForKey:UIKeyboardFrameEndUserInfoKey];

5.    CGRect keyboardRect = [self.view convertRect:[aValue CGRectValue] fromView:nil];

6.    //重新设置scrollView的size，使它还原到初始size

7.    CGRect viewFrame = [self.scrollView frame];

8.    viewFrame.size.height += keyboardRect.size.height;

9.    self.scrollView.frame = viewFrame;

10.    //还原滚动位置

11.    self.scrollView.contentOffset = offset;

12.    keyboardIsShown =   NO;

13. }

最后在View消失前，移除两个通知

1. - (void)viewWillDisappear:(BOOL)animated{

2.    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidShowNotification object:nil];

3.    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidHideNotification object:nil];

4. }