为 UITextField 增加键盘偏移的模板化写法

.h代码

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController<UITextFieldDelegate>
{

    int i_offset;    //偏移量
    int i_textFieldY;          //textField 的y 值
    int i_textFieldHeight;    //textField的高度
    IBOutlet UITextField *uitf_textField1;
    IBOutlet UITextField *uitf_textField2;
    IBOutlet UITextField *uitf_textField3;
}

@end

.m代码

#import "ViewController.h"

#define StautsBarHeight 20.0f

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    uitf_textField1.delegate = self;
    uitf_textField2.delegate = self;
    uitf_textField3.delegate = self;

    i_offset = ;    //默认偏移量为0
    i_textFieldY = ;
    i_textFieldHeight = ;

    //注册键盘监听消息
    [self registerKeyBoardNotification];

}

- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}

#pragma mark- UITextFieldDelegateMethod

- (void)textFieldDidBeginEditing:(UITextField *)textField
{
    NSLog(@"进入textFieldDidBeginEditing");  

    i_textFieldY = textField.frame.origin.y;
    i_textFieldHeight = textField.frame.size.height;

}

- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
    [textField resignFirstResponder];
    return YES;
}

#pragma mark- 键盘通知事件 ［核心代码］

//注册键盘监听消息
-(void)registerKeyBoardNotification
{
    //增加监听，当键盘出现或改变时收出消息    ［核心代码］
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardWillShow:)
                                                 name:UIKeyboardWillShowNotification
                                               object:nil];

    //增加监听，当键退出时收出消息
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardWillHide:)
                                                 name:UIKeyboardWillHideNotification
                                               object:nil];
    // 键盘高度变化通知，ios5.0新增的
#ifdef __IPHONE_5_0
    float version = [[[UIDevice currentDevice] systemVersion] floatValue];
    if (version >= 5.0) {
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillChangeFrameNotification object:nil];
    }
#endif
}

//当键盘出现或改变时调用
- (void)keyboardWillShow:(NSNotification *)aNotification
{
    //获取键盘的高度
    NSDictionary *userInfo = [aNotification userInfo];
    NSValue *aValue = [userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];
    CGRect keyboardRect = [aValue CGRectValue];
    int keyboardHeight = keyboardRect.size.height;

    //计算偏移量
    i_offset = keyboardHeight - (self.view.frame.size.height-(i_textFieldY+i_textFieldHeight));

    //进行偏移
    NSTimeInterval animationDuration = 0.30f;
    [UIView beginAnimations:@"ResizeForKeyBoard" context:nil];
    [UIView setAnimationDuration:animationDuration];
    float width = self.view.frame.size.width;
    float height = self.view.frame.size.height;
    if(i_offset > )
    {
        CGRect rect = CGRectMake(0.0f,StautsBarHeight-i_offset,width,height); //把整个view 往上提，肯定要用负数 y
        self.view.frame = rect;
    }  

    [UIView commitAnimations];
}

//当键退出时调用
- (void)keyboardWillHide:(NSNotification *)aNotification
{
    if(i_offset > )
    {
        //恢复到偏移前的正常量
        NSTimeInterval animationDuration = 0.30f;
        [UIView beginAnimations:@"ResizeForKeyBoard" context:nil];
        [UIView setAnimationDuration:animationDuration];
        float width = self.view.frame.size.width;
        float height = self.view.frame.size.height;
        CGRect rect = CGRectMake(0.0f,StautsBarHeight,width,height); //把整个view 往上提，肯定要用负数 y   注意self.view 的y 是从20开始的，即StautsBarHeight
        self.view.frame = rect;  

        [UIView commitAnimations];
    }  

    i_offset = ;
}