键盘的出现于隐藏（代码实现）=================================
1、通知案例：
#import "ViewController.h"
#import "UIView+FrameExtension.h" // 可以自己写，以后用着方便
#define kDeviceHeight [UIScreen mainScreen].bounds.size.height
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// 设置视图的背景色
self.view.backgroundColor = [UIColor lightGrayColor];
// 添加第一个文本框 假定位置
UITextField *firstField = [[UITextField alloc]initWithFrame:CGRectMake(50, 300, 200, 40)];
firstField.backgroundColor = [UIColor whiteColor];
[self.view addSubview:firstField];
// 添加第一个文本框
UITextField *secondField = [[UITextField alloc]initWithFrame:CGRectMake(firstField.x, firstField.bottom + 50, firstField.width , firstField.height)];
[self.view addSubview:secondField];
secondField.backgroundColor = [UIColor whiteColor];
// 注册键盘显示的通知
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(showKeyboard:) name:UIKeyboardWillShowNotification object:nil];
// 注册键盘隐藏的通知
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(hideKeyboard: ) name:UIKeyboardWillHideNotification object:nil];
}
// 键盘弹出时执行这个方法，
-(void)showKeyboard:(NSNotification *)notification{
// 定义一个文本框，指向正在编辑的文本框，也就是弹出键盘的文本框
UITextField *txtField;
// 今次遍历当前视图的所有子视图， subViews数组保存的是当前视图所有的子视图
for (UIView *subView in self.view.subviews) {
// 如果这个子视图是一个文本框的话，isKindOfClass方法可以判断某个变量是不是某个类型的变量
if ([subView isKindOfClass:[UITextField class]]) {
// 先把这个子视图转化为文本框
UITextField *tempField = (UITextField *)subView;
// 再判断这个文本框是不是正在编辑
if (tempField.isEditing ) {
// 如果这个文本框正在编辑，就是我要找的文本框，中断循环
txtField = tempField;
break;
}
}
}
NSLog(@"%@", notification);
// 获取通知的userInfo属性
NSDictionary *userInfoDict = notification.userInfo;
// 通过键盘通知的userInfo属性获取键盘的bounds
NSValue *value = [userInfoDict objectForKey:UIKeyboardBoundsUserInfoKey];
// 键盘的大小
CGSize keyboardSize = [value CGRectValue].size;
// 键盘高度
CGFloat keyboardHeight = keyboardSize.height;
CGFloat offset = kDeviceHeight - keyboardHeight - txtField.bottom ;
if (offset < 0 ) { //这种情况下需要上移
offset = offset - 10 ; //保存上移的高度
[UIView animateWithDuration:0.5 animations:^{
self.view.transform = CGAffineTransformMakeTranslation(0, offset );
}];
}
}
-(void)hideKeyboard:(NSNotification *)notification{
[UIView animateWithDuration:2 animations:^{
self.view.transform = CGAffineTransformIdentity;
}];
}
// 点击屏幕空白时隐藏键盘
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
[self.view endEditing:YES];
}
@end
二、辞去第一响应者
1、[self.view endEditing:YES]; //编辑结束 点击屏幕会退出键盘
2、[firstField resignFirstResponder]; //辞去第一响应者
3[firstField becomeFirstResponder]; //成为第一响应者