23.模态跳转和键盘

点击其中的textField的时候,视图控制器整体上移.避免键盘遮挡
RootViewController.m文件

#import "RootViewController.h"#import "SecondViewController.h"#define HEIGHT self.view.frame.size.height@interface RootViewController ()<UITextFieldDelegate>@property(nonatomic,retain)NSMutableArray *arr;@end@implementation RootViewController//vc的初始化方法,这个方法一般自己就调用了,不需要我们在额外的去调用,会初始化一些容器(数组)- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];    if (self) {        self.arr = [NSMutableArray array];    }    return self;}-(void)loadView{//--->self.view的加载    [super loadView];}#pragma mark 如果想重写父类的方法,首先用super去调用父类的方法,这样就可以保正原功能不变,然后在方法在再新添加的功能- (void)viewDidLoad {//视图已经加载完毕    [super viewDidLoad];    self.view.backgroundColor = [UIColor greenColor];    //视图的创建和铺设都在viewdidload方法里进行    UITextField *textField1 = [[UITextField alloc] initWithFrame:CGRectMake(100, 550, 150, 40)];    textField1.borderStyle = UITextBorderStyleRoundedRect;    [self.view addSubview:textField1];    textField1.delegate = self;    [textField1 release];    UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];    button.frame = CGRectMake(100, 400, 150, 40);    [button setTitle:@"下一页" forState:UIControlStateNormal];    [button addTarget:self action:@selector(click:) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:button];}- (void)click:(UIButton *)button{    //模态跳转    //创建一个secondViewController的对象    SecondViewController *secondVC = [[SecondViewController alloc] init];    //设置一下跳转的时候动画效果    [secondVC setModalTransitionStyle:UIModalTransitionStyleFlipHorizontal];    //进行跳转    [self presentViewController:secondVC animated:YES completion:^{    }];    [secondVC release];}- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField{    //当UITextField在较下面的时候,我们需要将view整体上移,当回收键盘时又还原回去    //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;}//等到编译结束时,再回到原来位置- (BOOL)textFieldShouldEndEditing:(UITextField *)textField{    //整个实在移动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    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)textFieldShouldReturn:(UITextField *)textField{    [textField resignFirstResponder];    return YES;}//下面的四个方法和上面的三个方法loadView,viewDidLoad,initWithNibName:bundle:都是UIViewController类自己的方法//视图将要出现- (void)viewWillAppear:(BOOL)animated{    [super viewWillAppear:animated];    NSLog(@"%s",__FUNCTION__);}//视图已经出现- (void)viewDidAppear:(BOOL)animated{    [super viewDidAppear:animated];    NSLog(@"%s",__FUNCTION__);}//视图将要消失- (void)viewWillDisappear:(BOOL)animated{    [super viewWillDisappear:animated];    NSLog(@"%s",__FUNCTION__);}//视图已经消失- (void)viewDidDisappear:(BOOL)animated{    [super viewWillDisappear:animated];    NSLog(@"%s",__FUNCTION__);}

效果截图如下所示


当点击下一页按钮时能够跳转到下一个视图控制器页面,当点击返回按钮时又能够分那会到之前的那个视图控制器页面(RootViewController)
SecondViewController.m文件如下

- (void)viewDidLoad {    [super viewDidLoad];    self.view.backgroundColor = [UIColor grayColor];    UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];    button.frame = CGRectMake(140, 160, 100, 40);    [button setTitle:@"返回" forState:UIControlStateNormal];    button.layer.borderWidth = 1;    button.layer.cornerRadius = 10;    [self.view addSubview:button];    [button addTarget:self action:@selector(backView:) forControlEvents:UIControlEventTouchUpInside];}- (void)backView:(UIButton *)button{    //点击回到上个页面    [self dismissViewControllerAnimated:YES completion:^{    }];}