iOS避免键盘遮挡输入方案

项目中经常会遇到这样的问题：一个tableView中有大量的textField，当点击屏幕底部的textfield时，由于键盘弹出挡住了textfield输入框里的内容，造成很差的用户体验，如下图，点击价格那一行，会出现图二这种效果（弹出的键盘完全遮盖了输入）。

图一：

图二：

解决思路：自定义一个textfield，声明一个公用方法  - (void)adjustTextFieldFrameWhenBeginEdtingWithView: keyBoardHeight:  并实现它，这个方法的作用是调整controller的view的y值使整个view上移，让被点击的textfield显示出来，建议在controller的view的textfield的代理方法 -(void)textFieldDidBeginEditing: 中获取自定义的textfield，并调用它的此方法（开始编辑时就调整view的y值）。

1.自定义textfield：

实现公用方法： - (void)adjustTextFieldFrameWhenBeginEdtingWithView:

 - (void)adjustTextFieldFrameWhenBeginEdtingWithView:(UIView *)view keyBoardHeight:(CGFloat)keyboadHeight
 {
     // 将控制器view保存起来
     self.adjustView = view;

     // 将textfield的坐标转换到控制器view坐标系中
     CGRect selfFrame =   [self convertRect:self.bounds toView:view];

     // 键盘的y值
     CGFloat keyBoardY = ;

     keyBoardY = [UIScreen mainScreen].bounds.size.height - keyboadHeight ;

     // 控制器view 要调整的高度
     CGFloat adjustY = selfFrame.origin.y + selfFrame.size.height + MARGIN - keyBoardY;

     if (adjustY > ) { // 调整高度大于0

         [UIView animateWithDuration:0.25 delay:0.0 options:UIViewAnimationOptionCurveEaseInOut animations:^{

             view.y = - adjustY;
         } completion:^(BOOL finished) {

         }];
     }else{
         [UIView animateWithDuration:0.25 delay:0.0 options:UIViewAnimationOptionCurveEaseInOut animations:^{
             view.y = ;
         } completion:^(BOOL finished) {

         }];
     }

 }

第13行用到了键盘的高度keyboadHeight，所以我们还需要在控制器中得到键盘的高度。

2.在控制器中获取键盘高度

在控制器的viewDidLoad方法中，注册通知（监听键盘出现的通知）。

 //增加监听，当键盘出现或改变时收出消息
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardWillShow:)
                                                 name:UIKeyboardWillShowNotification
                                               object:nil];

当键盘弹出时，获取键盘高度，并将键盘高度传入定义好的block

//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];
    CGFloat keyboadHeight = keyboardRect.size.height;

    // 调用保存好的block并将键盘高度传入
    self.editingBlock(keyboadHeight);
}

3.在控制器中调用textfield的自适应方法 - (void)adjustTextFieldFrameWhenBeginEdtingWithView: keyBoardHeight:

在控制器的textdelegate方法 - (void)textFieldDidBeginEditing: 中，定义block，在block中调用自定义textfield的自适应方法 - (void)adjustTextFieldFrameWhenBeginEdtingWithView: keyBoardHeight: ，并传入键盘高度。

之所以用block，是因为方法  - (void)textFieldDidBeginEditing:   被调用时，还没有获取到键盘高度，所以先将代码保存为block，等获取到键盘高度后再传入键盘高度，调用textfield的自适应键盘高度的方法 - (void)adjustTextFieldFrameWhenBeginEdtingWithView: keyBoardHeight:

block中调用自定义textfield的 - (void)adjustTextFieldFrameWhenBeginEdtingWithView: keyBoardHeight: 方法，并把键盘高度作为参数传入自定义textfield。

 #pragma YDTextFieldDelegate

 - (void)textFieldDidBeginEditing:(UITextField *)textField
 {
     YDTextField *tf = (YDTextField *)textField;

     __weak typeof(self) weakSelf = self;

     // 定义block，等待keyboardWillShow:方法获取键盘高度后调用
     self.editingBlock = ^(CGFloat keyboadHeight){

         // 此处调用自定义textfield的自适应方法
         [tf adjustTextFieldFrameWhenBeginEdtingWithView:weakSelf.view keyBoardHeight:keyboadHeight];

   };

 }

4. 输入完成后处理

在控制器viewDidLoad方法中，注册通知，监听键盘消失。

// 当键盘消失时响应
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardWillHide:)
                                                 name:UIKeyboardWillHideNotification object:nil];

键盘消失后，将调整后的view还原。

// 当键盘消失时调用
- (void)keyboardWillHide:(NSNotification *)note
{
    if ([note.name isEqualToString:UIKeyboardWillShowNotification]) {

    }else{
        [UIView animateWithDuration:0.25 animations:^{
            self.view.y = ;
        } completion:^(BOOL finished) {

        }];
    }
}

如此就完成了textfield的自适应，每次点击底部textfield，view会根据textfield的位置上移一段距离，不被键盘遮盖，效果如下：

图三：

图四：

附上demo代码：

控制器中代码：

 //
 //  ViewController.m
 //  TextfieldDemo
 //
 //  Created by heyode on 16/5/20.
 //  Copyright © 2016年 heyode. All rights reserved.
 //

 #import "ViewController.h"
 #import "YDTextField.h"
 #import "UIView+frame.h"
 // 键盘和当前活动textfield的间距
 #define MARGIN  15

 //定义随机色
 #define randomColor [UIColor colorWithRed:arc4random_uniform(256)/255.0 green:arc4random_uniform(256)/255.0 blue:arc4random_uniform(256)/255.0 alpha:1];

 typedef void(^textFieldDidBeginEditingBlock)(CGFloat keyboadHeight);
 #define BASECOUNT 30

 @interface ViewController ()<UITableViewDelegate,UITableViewDataSource,UITextFieldDelegate>
 /** tableView */
 @property (nonatomic,weak) UITableView *tableView;

 /** 数据源 */
 @property (nonatomic,strong) NSMutableArray *datas;

 /** block */
 @property (nonatomic,copy) textFieldDidBeginEditingBlock editingBlock;

 @end

 @implementation ViewController

 - (void)viewDidLoad {
     [super viewDidLoad];

     [self setUpDataSouce];
     [self setUpTableView];

     [self setUpNotification];
 }

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

     // 当键盘消失时响应
     [[NSNotificationCenter defaultCenter] addObserver:self
                                              selector:@selector(keyboardWillHide:)
                                                  name:UIKeyboardWillHideNotification object:nil];

 }

 // 当键盘消失时调用
 - (void)keyboardWillHide:(NSNotification *)note
 {
     if ([note.name isEqualToString:UIKeyboardWillShowNotification]) {

     }else{
         [UIView animateWithDuration:0.25 animations:^{
             self.view.y = ;
         } completion:^(BOOL finished) {

         }];
     }
 }

 //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];
     CGFloat keyboadHeight = keyboardRect.size.height;

     // 调用保存好的block并将键盘高度传入
     self.editingBlock(keyboadHeight);
 }

 - (void)setUpTableView
 {
     UITableView *tableView = [[UITableView alloc] initWithFrame:self.view.bounds style:UITableViewStylePlain];
     tableView.delegate = self;
     tableView.dataSource = self;
     [self.view addSubview:tableView];

 }

 - (void)setUpDataSouce
 {
     self.datas = [NSMutableArray array];

     for (int i = ; i < ; i++) {
         NSString *str = [NSString stringWithFormat:@"%i",i];
         [self.datas addObject:str];
     }

 }

 #pragma UITableviewDatasouce
 - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
 {
     return self.datas.count;
 }

 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
 {

     UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cell"];
     if (cell == nil) {
         cell = [[UITableViewCell alloc] initWithStyle: reuseIdentifier:@"cell"];
     }

     for (id view in cell.contentView.subviews) {
         [(UIView *)view removeFromSuperview];
     }

     cell.textLabel.text = self.datas[indexPath.row];

     YDTextField *tf = [[YDTextField alloc] initWithFrame:CGRectMake(, (cell.height - cell.height - )/, cell.width , cell.height - )];
     tf.tag = indexPath.row + BASECOUNT;

     tf.backgroundColor = randomColor;
     tf.delegate = self;

     [cell.contentView addSubview:tf];
     return cell;
 }

 #pragma YDTextFieldDelegate

 - (void)textFieldDidBeginEditing:(UITextField *)textField
 {
     YDTextField *tf = (YDTextField *)textField;

     __weak typeof(self) weakSelf = self;

     // 定义block，等待keyboardWillShow:方法获取键盘高度后调用
     self.editingBlock = ^(CGFloat keyboadHeight){

         // 此处调用自定义textfield的自适应方法
         [tf adjustTextFieldFrameWhenBeginEdtingWithView:weakSelf.view keyBoardHeight:keyboadHeight];

   };

 }

 @end

自定义textfield代码：

 //
 //  YDTextField.m
 //  TextfieldDemo
 //
 //  Created by heyode on 16/5/20.
 //  Copyright © 2016年 heyode. All rights reserved.
 //

 #import "YDTextField.h"
 #import "UIView+frame.h"

 // 键盘和当前活动textfield的间距
 #define MARGIN  15

 @interface YDTextField()
 @property (weak, nonatomic) UIView *adjustView;
 /**键盘高度 */
 @property (nonatomic,assign) CGFloat keyboadHeight;

 @end

 @implementation YDTextField

 - (instancetype)initWithFrame:(CGRect)frame
 {
     if (self = [super initWithFrame:frame]) {
         [self initialize];

     }
     return self;
 }

 - (void)awakeFromNib
 {

      [self initialize];
 }

 - (void)layoutSubviews
 {
     [super layoutSubviews];
 }

 - (void)initialize
 {

     // 点击return时，结束编辑状态
     [self addTarget:self action:@selector(endEditing:) forControlEvents:UIControlEventEditingDidEndOnExit];
 }

 - (void)adjustTextFieldFrameWhenBeginEdtingWithView:(UIView *)view keyBoardHeight:(CGFloat)keyboadHeight
 {
     // 将控制器view保存起来
     self.adjustView = view;

     // 将textfield的坐标转换到控制器view坐标系中
     CGRect selfFrame =   [self convertRect:self.bounds toView:view];

     // 键盘的y值
     CGFloat keyBoardY = ;

     keyBoardY = [UIScreen mainScreen].bounds.size.height - keyboadHeight ;

     // 控制器view 要调整的高度
     CGFloat adjustY = selfFrame.origin.y + selfFrame.size.height + MARGIN - keyBoardY;

     if (adjustY > ) { // 调整高度大于0

         [UIView animateWithDuration:0.25 delay:0.0 options:UIViewAnimationOptionCurveEaseInOut animations:^{

             view.y = - adjustY;
         } completion:^(BOOL finished) {

         }];
     }else{
         [UIView animateWithDuration:0.25 delay:0.0 options:UIViewAnimationOptionCurveEaseInOut animations:^{
             view.y = ;
         } completion:^(BOOL finished) {

         }];
     }

 }

 @end