UIViewController

UIViewController:视图控制器
作用:
1.控制视图显⽰示,响应事件
2.分担AppDelegate的工作
3.实现模块独立,提高复用性
功能:
1.控制视图大小变换、布局视图、响应事件。
2.检测以及处理内存警告。
3.检测以及处理屏幕旋转。
4.检测视图的切换

MVC概述
UIViewController是MVC设计模式的核心。
MVC是一个框架级的设计模式。
M是Model,主要用于建立数据模型(即数据的结构)
V是View,我们能看到的所有控件都是view,view主要的功能是展示数据。
C是Controller控制器,主要是控制M和V的通信

为什么使用自定义视图类
UIViewController自带一个空的view,与需求不符合。
视图控制器只负责控制视图显示,响应事件

检测屏幕旋转

视图控制器本身能检测到屏幕的旋转,如果要处理屏幕旋转,需要重写几个方法:1.supportedInterfaceOrientations(设置设备支持旋转的方向)2.willRotateToInterfaceOrientation:duration:(暂停音乐、关闭视图交互等)3.willAnimateRotationToInterfaceOrientation:duration:(添加⾃定义动画等)4.didRotateFromInterfaceOrientation:(播放⾳乐、打开视图交互等)。

视图处理

注意视图控制器会自动调整view的⼤⼩以适应屏幕旋转,bounds被修改,触发view的layoutSubviews⽅法。view重写layoutSubviews方法,根据设备方向,重新布局。[UIApplication shareApplication].statusBarOrientation提供设备当前方向。

                        练习题修改LoginView上视图的布局。重写view的layoutSubviews方法。实现横屏时,三个控件显示在同一行。横竖屏切换时,回收已经出现的键盘

处理内存警告

控制器能监测内存警告,以便我们避免内存不够引起的crash。 在定义的controller子类中重写didReceiveMemoryWarning⽅法。 释放暂时不使用的资源。(数据对象、图像)

                        练习题重写didReceiveMemoryWarning方法。NSLog输出__Function__模拟内存警告:模拟器 -> 硬件 -> 模拟内存警告。查看方法执行- (void)didReceiveMemoryWarning{    [super didReceiveMemoryWarning];//根视图已经加载过,根视图未显示    if ([self isViewLoaded] == YES && self.view.window== nil) {//将根视图销毁        self.view = nil;    }}

容器视图控制器
常用方法

self.view显示:viewWillAppear: 和 viewDidAppear:self.view消失:viewWillDisappear: 和 viewDidDisappear:当self.view添加到父视图上时,执行appear方法: 当self.view从父视 图上移除时,执行disappear方法

演示执行顺序

定义FirstViewController、SecondViewController类,first作为window 的根视图控制器。将SecondViewController的view添加到FirstViewController的view上。 将SecondViewController的view移除。 查看SecondViewController中4个⽅法的执行顺序

#import "rootViewController.h"#define HEIGHT self.view.frame.size.height#import "LTView.h"#import "SecondViewController.h"@interface rootViewController ()<UITextFieldDelegate>@property(nonatomic, retain)NSMutableArray *arr;@end@implementation rootViewController// 视图控制器的初始化方法,这个方法一般自己就调用了,不需要我们再额外的去调用.它可以用来初始化一些容器,比如数组,字典等- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];    if (self) {        self.arr = [NSMutableArray array];    }    NSLog(@"%s", __FUNCTION__);    return self;}- (void)loadView{    [super loadView];    [LTView load];    NSLog(@"%s", __FUNCTION__);    // 主要针对self.view 进行创建 属于懒人加载模式(lazyingloading)}#pragma mark 如果想重写父类的方法,首先先用super去调用父类的方法,这样可以保证原功能不变,然后在方法里再写新添加的功能// 视图加载- (void)viewDidLoad {    [super viewDidLoad];    self.view.backgroundColor = [UIColor magentaColor];    NSLog(@"%s", __FUNCTION__);    // 视图的创建和铺设都在viewDidLord方法里进行    // 铺3个testField    UITextField *textField1 = [[UITextField alloc] initWithFrame:CGRectMake(100, 200, 150, 40)];    textField1.layer.borderWidth = 1;    textField1.layer.cornerRadius = 10;    [self.view addSubview:textField1];    [textField1 release];    textField1.delegate = self;    UITextField *textField2 = [[UITextField alloc] initWithFrame:CGRectMake(100, 300, 150, 40)];    textField2.layer.borderWidth = 1;    textField2.layer.cornerRadius = 10;    [self.view addSubview:textField2];    [textField2 release];    textField2.delegate = self;    UITextField *textField3 = [[UITextField alloc] initWithFrame:CGRectMake(100, 400, 150, 40)];    textField3.layer.borderWidth = 1;    textField3.layer.cornerRadius = 10;    [self.view addSubview:textField3];    [textField3 release];    textField3.delegate = self;    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];    button.frame = CGRectMake(100, 500, 150, 40);    [button setTitle:@"下页" forState:UIControlStateNormal];    [button addTarget:self action:@selector(click:) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:button];    button.layer.borderWidth = 1;    button.layer.cornerRadius = 10;    // Do any additional setup after loading the view.}- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField{    // 整个是在移动self.view,父视图的移动会让所有的子视图一同移动,而且相对父视图的坐标位置不会发生变化,所以,可以沿用上一个方法的判断    // 只要输入框被激活,就会触发这方法    if (textField.frame.origin.y > HEIGHT / 2) {        // 先做一个差值        CGFloat height = textField.frame.origin.y - HEIGHT / 2;        self.view.center = CGPointMake(self.view.center.x, self.view.center.y - height);    }    return YES;}- (BOOL)textFieldShouldEndEditing:(UITextField *)textField{    // HIGHT 为view视图高度    if (textField.frame.origin.y > HEIGHT / 2) {        // 先做一个差值        CGFloat height = textField.frame.origin.y - HEIGHT / 2;        self.view.center = CGPointMake(self.view.center.x, self.view.center.y + height);    }    return YES;}// 右上角点击索引方法名 相当于在方法列表中添加注释#pragma mark 视图将要出现- (void)viewWillAppear:(BOOL)animated{    [super viewWillAppear:animated];    NSLog(@"%s", __FUNCTION__);}// 手动加警告 报黄//#warning 这个方法是视图已经出现的意思- (void)viewDidAppear:(BOOL)animated{    [super viewDidAppear:animated];    NSLog(@"%s", __FUNCTION__);}- (void)viewWillDisappear:(BOOL)animated{    [super viewWillDisappear:animated];    NSLog(@"%s", __FUNCTION__);}- (void)click:(UIButton *)button{//    [UIColor clearColor];//    CGFloat a = arc4random() % 256 / 255.0;//    CGFloat b = arc4random() % 256 / 255.0;//    CGFloat c = arc4random() % 256 / 255.0;//    self.view.backgroundColor = [UIColor colorWithRed:a  green:b blue:c alpha:1];//    NSLog(@"%g,%g,%g", a, b, c);    // 创建一个secondVC对象    SecondViewController *secondVC = [[SecondViewController alloc] init];    // 设置一下跳转的时候动画效果//    [secondVC setModalTransitionStyle:UIModalTransitionStyleCrossDissolve];    [secondVC setModalTransitionStyle:    UIModalTransitionStyleFlipHorizontal];//    [secondVC setModalTransitionStyle:UIModalTransitionStyleCoverVertical];//    [secondVC setModalTransitionStyle:UIModalTransitionStylePartialCurl];    // 进行跳转    [self presentViewController:secondVC animated:YES completion:^{     }];    [secondVC release];}// 监控当前内存信息- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}@end

#import "SecondViewController.h"@interface SecondViewController ()@end@implementation SecondViewController- (void)viewDidLoad {    [super viewDidLoad];    UIButton *button = [ UIButton buttonWithType:UIButtonTypeSystem];    button.frame = CGRectMake(100, 100, 100, 30);    button.layer.borderWidth = 1;    button.layer.cornerRadius = 10;    [self.view addSubview:button];    [button setTitle:@"返回" forState:UIControlStateNormal];    [button addTarget:self action:@selector(click:) forControlEvents:UIControlEventTouchUpInside];    self.view.backgroundColor = [UIColor orangeColor];    // Do any additional setup after loading the view.}- (void)click:(UIButton *)button{    // 点击返回,回到前一个页面    [self dismissViewControllerAnimated:YES completion:^{//        <#code#>    }];}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}@end

#import <UIKit/UIKit.h>@interface LTView : UIView<UITextFieldDelegate>// 因为要在类的外面获取输入框的内容并修改Label的标题,所以把这两部分属性写在.h文件中@property(nonatomic, retain)UILabel *MyLaber;@property(nonatomic, retain)UITextField *MyTextField;@end

#import "LTView.h"@implementation LTView// 重写默认的初始化方法- (instancetype)initWithFrame:(CGRect)frame{    self = [super initWithFrame:frame];    if (self) {        // 模块化        [self createView1];//        [self createView2];    }    return self;}- (void)createView1{    // 创建两个子视图,一个是label,一个是textField    self.MyLaber = [[UILabel alloc] initWithFrame:CGRectMake(50, 100, 100, 40)];    self.MyLaber.backgroundColor = [UIColor orangeColor];    self.MyTextField = [[UITextField alloc] initWithFrame:CGRectMake(180, 100, 180, 40)];    self.MyTextField.backgroundColor = [UIColor cyanColor];    self.MyTextField.delegate = self;    [self addSubview:self.MyLaber];    [self addSubview:self.MyTextField];    [self.MyLaber release];    [self.MyTextField release];}- (void)createView2{    self.MyLaber = [[UILabel alloc] initWithFrame:CGRectMake(50, 160, 100, 40)];    self.MyLaber.backgroundColor = [UIColor yellowColor];    [self addSubview:self.MyLaber];    [self.MyLaber release];    self.MyTextField = [[UITextField alloc] initWithFrame:CGRectMake(180, 160, 180, 40)];    self.MyTextField.backgroundColor = [UIColor blueColor];    [self addSubview:self.MyTextField];    [self.MyTextField release];}- (void)dealloc{    [self.MyTextField release];    [self.MyLaber release];    [super dealloc];}- (BOOL)textFieldShouldReturn:(UITextField *)textField{    [textField resignFirstResponder];    return YES;}@end