[iOS]利用通知实现监听系统键盘

//// ViewController.m// text//// Created by 李东旭 on 16/1/22.// Copyright © 李东旭. All rights reserved.//#import <UIKit/UIKit.h>#import "ViewController.h"@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad {[super viewDidLoad];UITextView *textV = [[UITextView alloc] initWithFrame:self.view.bounds];[self.view addSubview:textV];// 1. 添加通知[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyBoardChange:) name:UIKeyboardWillShowNotification object:nil];// 键盘将要出现 UIKeyboardWillShowNotification// 键盘已经出现 UIKeyboardDidShowNotification// 键盘将要隐藏 UIKeyboardWillHideNotification// 键盘已经隐藏 UIKeyboardDidHideNotification}// 2. 键盘已经出现调用的触发方法- (void)keyBoardChange:(NSNotification *)noti{NSLog(@"%@", noti);// 打印noti/*0x7f84584d1000 {name = UIKeyboardDidShowNotification; userInfo = {// 键盘动画执行节奏UIKeyboardAnimationCurveUserInfoKey = 7;// 键盘动画的时间UIKeyboardAnimationDurationUserInfoKey = "0.25";// 键盘的boundsUIKeyboardBoundsUserInfoKey = "NSRect: {{0, 0}, {375, 258}}";// 键盘的起始centerUIKeyboardCenterBeginUserInfoKey = "NSPoint: {187.5, 796}";// 键盘的结束centerUIKeyboardCenterEndUserInfoKey = "NSPoint: {187.5, 538}";// 键盘开始动画前的位置（也就是消失时）UIKeyboardFrameBeginUserInfoKey = "NSRect: {{0, 667}, {375, 258}}";// 键盘结束动画后的位置（也就是弹出了）UIKeyboardFrameEndUserInfoKey = "NSRect: {{0, 409}, {375, 258}}";UIKeyboardIsLocalUserInfoKey = 1;}}*/// 3. 那么如何获取这个值呢NSDictionary *noKey = [noti userInfo];NSValue *value = noKey[@"UIKeyboardBoundsUserInfoKey"];// 注意，这个的value 是CGRect类型的（所以下面必须调用CGRectValue方法NSLog(@"%f", [value CGRectValue].size.height);}@end

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