iOS开发中,经常会遇到输入框被键盘挡住的情况,通过查阅资料和自己的思考,想出来下面这个方法:
基本思路:
- 在点击UITextField时,会自动调用 textFieldShouldBeginEditing 方法,在该方法中获取光标高度;
- 利用通知中心监听 UIKeyboardWillShowNotification ,在监听方法中可以获取到键盘高度,将键盘高度与光标高度相比较:如果键盘高度大于光标高度,则调整self.view的frame,使UITextField可以显示出来,将差值保存下来;如果小于,不做操作.
- 利用通知中心监听 name:UIKeyboardWillHideNotification ,在监听方法中判断差值是否大于0:如果大于,说明已经调整过self.view的frame,现在需要调整回来;如果小于,不做操作.
这就是实现的基本思路,在此基础上,就可以现在了.基础比较好的可以自己去研究了.如果嫌麻烦,可以接着看.我接着写具体实现过程.
我做了一个Demo,其中包含3个UITextField,自上而下:tfAccount,tfPassword,tfEmail.
第一步: 实现代理
- 实现代理:
_tfPassword.delegate = self; - 遵守协议: UITextFieldDelegate
- 实现方法:
- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField{}
第二步: 获取点击的UITextField距底部的高度
#pragma mark- UITextFieldDelegate
- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField {
if ([textField isEqual:self.tfAccount]) {
_cursorHeight = self.view.frame.size.height - CGRectGetMaxY(textField.frame);
}else if ([textField isEqual:self.tfPassword]) {
_cursorHeight = self.view.frame.size.height - CGRectGetMaxY(textField.frame);
}else if ([textField isEqual:self.tfEmail]) {
_cursorHeight = self.view.frame.size.height - CGRectGetMaxY(textField.frame);
}
return YES;
}
其中,在类的延展中声明_cursorHeight: float _cursorHeight; 这是光标距底部的高度.
第三步:通知,监听
- (void)viewDidLoad {
[super viewDidLoad];
//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];
//增加监听，当键退出时收出消息
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillHide:)
name:UIKeyboardWillHideNotification
object:nil];
}
//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];
float keyboardHeight = keyboardRect.size.height;
_spacingWithKeyboardAndCursor = keyboardHeight - _cursorHeight;
if (_spacingWithKeyboardAndCursor > 0) {
[UIView animateWithDuration:kAnimationDuration animations:^{
//将视图的Y坐标向上移动offset个单位，以使下面腾出地方用于软键盘的显示
self.view.frame = CGRectMake(0.0f, -(_spacingWithKeyboardAndCursor + 5.0f), self.view.frame.size.width, self.view.frame.size.height);
}];
}
}
//当键退出时调用
- (void)keyboardWillHide:(NSNotification *)aNotification {
if (_spacingWithKeyboardAndCursor > 0) {
[UIView animateWithDuration:kAnimationDuration animations:^{
//将视图的Y坐标向上移动offset个单位，以使下面腾出地方用于软键盘的显示
self.view.frame = CGRectMake(0.0f, 0.0f, self.view.frame.size.width, self.view.frame.size.height);
}];
}
}
其中,在类的延展中声明_spacingWithKeyboardAndCursor: float _spacingWithKeyboardAndCursor; 这是光标与键盘之间的间隔.
至此,一个最简单的Demo完成了.为了便于理解,除了必要的代码,其他任何有利于完善的代码都没有添加.
呈上代码:
(注:这是ViewController.m中的代码,其他页面没有添加任何代码,大家可以直接新建一个项目,将代码拷过去,进行测试)
//
// ViewController.m
// ChangeKeyboardHeightDemo
//
// Created by Suzhenyu on 16/3/16.
// Copyright © 2016年 apple. All rights reserved.
//
#import "ViewController.h"
static const CGFloat kSpacing = 8.0f; //间隔
static const NSTimeInterval kAnimationDuration = 1.0f; //动画时间
@interface ViewController ()<UITextFieldDelegate>
{
float _cursorHeight; //光标距底部的高度
float _spacingWithKeyboardAndCursor; //光标与键盘之间的间隔
}
@property (nonatomic, strong) UITextField *tfAccount;
@property (nonatomic, strong) UITextField *tfPassword;
@property (nonatomic, strong) UITextField *tfEmail;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor darkGrayColor];
[self.view addSubview:self.tfAccount];
[self.view addSubview:self.tfPassword];
[self.view addSubview:self.tfEmail];
//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];
//增加监听，当键退出时收出消息
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillHide:)
name:UIKeyboardWillHideNotification
object:nil];
}
//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];
float keyboardHeight = keyboardRect.size.height;
_spacingWithKeyboardAndCursor = keyboardHeight - _cursorHeight;
if (_spacingWithKeyboardAndCursor > 0) {
[UIView animateWithDuration:kAnimationDuration animations:^{
//将视图的Y坐标向上移动offset个单位，以使下面腾出地方用于软键盘的显示
self.view.frame = CGRectMake(0.0f, -(_spacingWithKeyboardAndCursor), self.view.frame.size.width, self.view.frame.size.height);
}];
}
}
//当键退出时调用
- (void)keyboardWillHide:(NSNotification *)aNotification {
if (_spacingWithKeyboardAndCursor > 0) {
[UIView animateWithDuration:kAnimationDuration animations:^{
//将视图的Y坐标向上移动offset个单位，以使下面腾出地方用于软键盘的显示
self.view.frame = CGRectMake(0.0f, 0.0f, self.view.frame.size.width, self.view.frame.size.height);
}];
}
}
#pragma mark- 懒加载
-(UITextField *)tfAccount {
if (!_tfAccount) {
_tfAccount = [[UITextField alloc] initWithFrame:CGRectMake(kSpacing, self.view.frame.size.height - 180, self.view.frame.size.width - kSpacing * 2.0, 30)];
_tfAccount.backgroundColor = [UIColor whiteColor];
_tfAccount.placeholder = @"请输入账号";
_tfAccount.delegate = self;
}
return _tfAccount;
}
-(UITextField *)tfPassword {
if (!_tfPassword) {
_tfPassword = [[UITextField alloc] initWithFrame:CGRectMake(kSpacing, self.view.frame.size.height - 120, self.view.frame.size.width - kSpacing * 2.0, 30)];
_tfPassword.backgroundColor = [UIColor whiteColor];
_tfPassword.placeholder = @"请输入密码";
_tfPassword.delegate = self;
}
return _tfPassword;
}
-(UITextField *)tfEmail {
if (!_tfEmail) {
_tfEmail = [[UITextField alloc] initWithFrame:CGRectMake(kSpacing, self.view.frame.size.height - 60, self.view.frame.size.width - kSpacing * 2.0, 30)];
_tfEmail.backgroundColor = [UIColor whiteColor];
_tfEmail.placeholder = @"请输入邮箱";
_tfEmail.delegate = self;
}
return _tfEmail;
}
#pragma mark- UITextFieldDelegate
- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField {
if ([textField isEqual:self.tfAccount]) {
_cursorHeight = self.view.frame.size.height - CGRectGetMaxY(textField.frame);
}else if ([textField isEqual:self.tfPassword]) {
_cursorHeight = self.view.frame.size.height - CGRectGetMaxY(textField.frame);
}else if ([textField isEqual:self.tfEmail]) {
_cursorHeight = self.view.frame.size.height - CGRectGetMaxY(textField.frame);
}
return YES;
}
@end
