UImageView显示图片

用于显示图片视图

• 属性：
  image: UIImage类型，用于设置要显示的图片。
  如何构建UIImage类型的对象，使用imageNamed：方法即可。
  contentMode:设置内容的显示模式，此属性是枚举类型的，有三个选项
  1.UIViewContentModeScaleToFill默认值，会拉伸图片
  2.UIViewContentModeScaleAspectFit保持宽高比，并且看到图片的全部，如果图片不合适，可能在图片框中留出空
  3.UIViewContentModeScaleAspectFill保持宽高比，填满图片框不会留白，但是可能会有图片过大时超出图片框的范围，此时要配合一个设置，即多出部分剪切掉clipsToBounds = YES

//    UIImageView *imageView = [[UIImageView alloc]initWithFrame:CGRectMake(50, 50, 300, 400)];
//    imageView.backgroundColor = [UIColor redColor];
//    imageView.image = [UIImage imageNamed:@"timg"];
    
//    /*UIViewContentModeScaleToFill,会拉伸填充满
//    UIViewContentModeScaleAspectFit,会留白
//    UIViewContentModeScaleAspectFill,会切割超出部分 但要配合clipsToBounds 使用
//     */
//    imageView.contentMode = UIViewContentModeBottom;
//    imageView.clipsToBounds = YES;
//    [self.view addSubview:imageView];
    //如果使用initWithImage初始化方法创建 UIImageView对象，不设置frame,那么frame就是图片的原尺寸大小
    UIImageView *imageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"timg"]];
    [self.view addSubview:imageView];

• 练习对话框练习及封装，return用委托方法处理事件且不收键盘

#import "MyViewController.h"
//使用 系统委托 第一件事 遵守协议 委托方类名+Delegate
@interface MyViewController ()<UITextFieldDelegate>
@property(nonatomic,assign)NSInteger y;
@end

@implementation MyViewController
//使用 系统委托 第二件事 实现协议中 的代理方法
- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
    [self senderMessage:textField isMe:YES];
    return YES;
}
- (void)viewDidLoad {
    [super viewDidLoad];
    self.y = 20;
    UITextField *meTF = [[UITextField alloc]initWithFrame:CGRectMake(20, self.y, self.view.frame.size.width - 20 - 20, 40)];
    meTF.borderStyle = UITextBorderStyleRoundedRect;
    meTF.placeholder = @"请输入聊天内容";
//    //添加点击return的事件方法 didEndOnExit
//    [meTF addTarget:self action:@selector(sendMeMessage:) forControlEvents:UIControlEventEditingDidEndOnExit];
    //使用 系统委托 第三件事 设置委托方的代理人是谁
    meTF.delegate =  self;
    [self.view addSubview:meTF];
    self.y += meTF.frame.size.height + 20;
    UITextField *otherTF = [[UITextField alloc]initWithFrame:CGRectMake(20, self.y, meTF.frame.size.width, 40)];
    otherTF.borderStyle = UITextBorderStyleRoundedRect;
    otherTF.placeholder = @"请输入聊天内容";
    [otherTF addTarget:self action:@selector(sendOtherMessage:) forControlEvents:UIControlEventEditingDidEndOnExit];
    [self.view addSubview:otherTF];
    self.y += otherTF.frame.size.height + 20;
}
////meTF 的事件方法
//-(void)sendMeMessage:(UITextField*)sender{
//    [self senderMessage:sender isMe:YES];
//}
-(void)sendOtherMessage:(UITextField*)sender{
   [self senderMessage:sender isMe:NO];
}
-(void)senderMessage:(UITextField*)sendTextField isMe:(BOOL)isMe
{
    UILabel *label = [[UILabel alloc]init];
    label.text = sendTextField.text;
    label.numberOfLines= 0;
    //根据内容获取实际 宽 高
    CGRect labelRect = [label textRectForBounds:CGRectMake(0, 0, 200, 999) limitedToNumberOfLines:0];
    label.frame = CGRectMake(isMe ? 20 : 30, 20, labelRect.size.width, labelRect.size.height);
    CGFloat imageViewWidth = label.frame.size.width +50;
    CGFloat imageViewHeight= label.frame.size.width +40;
    
    UIImageView *imageView = [[UIImageView alloc]init];
    imageView.image = [UIImage imageNamed:isMe ? @"气泡右" : @"气泡左"];
    imageView.frame= CGRectMake(isMe ? self.view.frame.size.width - imageViewWidth - 20 : 20 , self.y, imageViewWidth, imageViewHeight);
    //将label添加到 imageView上
    [imageView addSubview:label];
    //将imageView添加到 self.view上
    [self.view addSubview:imageView];
    self.y += imageViewHeight +20;
    sendTextField.text = @"";
}

• 练习二，文本框密码登陆

@interface MyViewController ()
@property(nonatomic,strong)UITextField *usernameTextField;
@property(nonatomic,strong)UITextField *passwordTextField;
@property(nonatomic,strong)UIButton *button;
@property(nonatomic,strong)UILabel *label;
@property(nonatomic,assign)NSInteger i;
@end

@implementation MyViewController
/*
 声明一个属性
 声明一个 _属性名 变量
 生成一个setter方法 set属性名
 生成一个getter方法 直接使用属性名做方法名
 */
//在第一次使用该属性的 getter方法的 创建对象
//懒得不能在懒了 在使用前不创建不行了z才去创建
//延迟加载 （属性的懒加载）
-(UITextField *)usernameTextField{
    if(!_usernameTextField)
    _usernameTextField = [[UITextField alloc]init];
    _usernameTextField.frame = CGRectMake(20, 100, 300, 40);
    _usernameTextField.borderStyle = UITextBorderStyleRoundedRect;
    _usernameTextField.placeholder = @"请输入用户名";
    _usernameTextField.textAlignment = NSTextAlignmentCenter;
    //给文本框 添加事件 当文本框编辑是会自动调用
    [_usernameTextField addTarget:self action:@selector(textFieldEditing:) forControlEvents:UIControlEventEditingChanged];
    [self.view addSubview:_usernameTextField];
    
    return _usernameTextField;
    
}
-(UITextField *)passwordTextField
{   if(!_passwordTextField)
    _passwordTextField = [[UITextField alloc]init];
    _passwordTextField.frame = CGRectMake(20, 200, 300, 40);
    _passwordTextField.borderStyle = UITextBorderStyleRoundedRect;
    _passwordTextField.placeholder = @"请输入密码";
    _passwordTextField.textAlignment = NSTextAlignmentCenter;
    //给文本框 添加事件 当文本框编辑是会自动调用
    [_passwordTextField addTarget:self action:@selector(textFieldEditing:) forControlEvents:UIControlEventEditingChanged];
    [self.view addSubview:_passwordTextField];
    
    return _passwordTextField;
}
-(UIButton*)button
{    if(!_button)
   {
       _button = [UIButton buttonWithType:UIButtonTypeSystem];
       _button.frame = CGRectMake(20, 280, 300, 40);
       [_button setBackgroundImage:[UIImage imageNamed:@"BTN"] forState:UIControlStateNormal];
       [_button setBackgroundImage:[UIImage imageNamed:@"BTN2"] forState:UIControlStateHighlighted];
       [_button setBackgroundImage:[UIImage imageNamed:@"disable"] forState:UIControlStateDisabled];
       [_button addTarget:self action:@selector(userLogin:) forControlEvents:UIControlEventTouchUpInside];
       //设置button为非激活状态（失效状态）
       _button.enabled = NO;
       [self.view addSubview:_button];
   }
    return _button;
}
-(UILabel *)label
{
    if(!_label){
   _label = [[UILabel alloc]initWithFrame:CGRectMake(20, 350, 300, 40)];
    _label.backgroundColor = [UIColor whiteColor];
        [self.view addSubview:_label];
  }
    return _label;
}
-(void)textFieldEditing:(UITextField*)sender
{
    if(self.usernameTextField.text.length != 0 && self.passwordTextField.text.length !=0)
        //如果两个文本框中都有内容 button 激活
    {
        self.button.enabled = YES;
    }
    else
    {
        self.button.enabled = NO;
    }
}
- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
//    NSInteger d = self.i +1;//getter
//    self.i = 10+20;//setter
//    self.i += self.i + 20;//前面 setter 后面 getter
//    NSInteger d2 = [self i] +1;//getter
//    [self setI:10 +20];//setter
//    [self setI: [self i] + 20];//前面 setter 后面 getter
    [self usernameTextField];
    [self passwordTextField];
    [self button];
    [self label];
    
}
-(void)userLogin:(UIButton*)sender
{
    if([self.usernameTextField.text isEqualToString:@"abc"]&&[self.passwordTextField.text isEqualToString:@"123"]){
        self.label.text =@"登陆成功";
        self.label.textAlignment = NSTextAlignmentCenter;
        
    }
    self.label.text = @"登陆失败";
}