IOS 开发笔记-基础 UI（6）照片浏览器（控件的懒加载）

浏览数：40 / 时间：2015年06月11日

使用UIImageView、UILabel、UIButton实现一个综合小案例

功能分析

(1)点击箭头切换序号、图片、描述

(2)如果是首张图片，左边箭头不能点击

(3)如果是尾张图片，右边箭头不能点击

步骤分析

(1)搭建UI界面

(2)监听按钮点击

切换序号、图片、描述

技术分享

1. 界面分析

1> 需要读取或修改的属性的控件

// 序号标签

// 图片

// 图片描述

// 左边按钮

// 右边按钮

2> 需要监听响应事件的对象，需要添加监听方法

// 左边按钮

// 右边按钮

uiimage 是图片，不是控件，他的父类为NSObject，UIImageView是加载图片的控件，父类为UIView

完全的代码编写界面（复习回忆）

#import "ViewController.h"

@interface ViewController ()
//序号标签
@property (nonatomic, strong) UILabel *noLabel;
//图片
@property (nonatomic, strong) UIImageView *icon;
//图片描述
@property (nonatomic, strong) UILabel *descLabel;
//左边按钮
@property (nonatomic, strong) UIButton *leftButton;
//右边按钮
@property (nonatomic, strong) UIButton *rightButton;
@end

@implementation ViewController

//初始化工作
//viewDidLoad是视图加载完成后调用的方法，通常在此方法中执行视图控制器的初始化工作
- (void)viewDidLoad {
    [super viewDidLoad];
    //实例化控件
    //1、序号标签的编写
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 20, 320, 40)];
    label.text = @"1/5";
    //居中对齐
    label.textAlignment = NSTextAlignmentCenter;
    [self.view addSubview:label];
    //记录改变
    self.noLabel = label;
    
    //2、图片控件
    CGFloat imageW = 200;
    CGFloat imageH = 200;
    CGFloat imageX = (320 - imageW) / 2;
    CGFloat imageY = 80;
    //实例化一个图像视图
    UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(imageX, imageY, imageW, imageH)];
    //实例化一个图像
    UIImage *image = [UIImage imageNamed:@"biaoqingdi"];
    //把图片显示到imageView
    imageView.image = image;
    [self.view addSubview:imageView];
    //记录下改变
    self.icon = imageView;
    
    //3、图片描述 label 控件
    UILabel *label1 = [[UILabel alloc] initWithFrame:CGRectMake(0, 300, 300, 80)];
    label1.text = @"发发发";
    //居中对齐
    label1.textAlignment = NSTextAlignmentCenter;
    [self.view addSubview:label1];
    //记录改变
    self.descLabel = label1;
    
    //4、左边的按钮
    UIButton *leftBtn = [[UIButton alloc] init];
    //设置按钮的背景图
    [leftBtn setBackgroundImage:[UIImage imageNamed:@"left_normal"] forState:UIControlStateNormal];
    [leftBtn setBackgroundImage:[UIImage imageNamed:@"left_highlighted"] forState:UIControlStateHighlighted];
    //设置按钮的大小
    leftBtn.frame = CGRectMake(0, 0, 40, 40);
    //设置按钮的位置
    leftBtn.center = CGPointMake(self.icon.frame.origin.x / 2, self.icon.center.y);
    
    [self.view addSubview:leftBtn];
    self.leftButton = leftBtn;
    
    //5、右边的按钮
    UIButton *rightBtn = [[UIButton alloc] init];
    //设置按钮的背景图
    [rightBtn setBackgroundImage:[UIImage imageNamed:@"right_normal"] forState:UIControlStateNormal];
    [rightBtn setBackgroundImage:[UIImage imageNamed:@"right_highlighted"] forState:UIControlStateHighlighted];
    //设置按钮的大小
    rightBtn.frame = CGRectMake(0, 0, 40, 40);
    //设置按钮的位置
    rightBtn.center = CGPointMake(self.view.frame.size.width - self.icon.frame.origin.x / 2, self.icon.center.y);
    
    [self.view addSubview:rightBtn];
    self.leftButton = rightBtn;
}

@end

完整的代码如下：

#import "ViewController.h"

@interface ViewController ()
//序号标签
@property (nonatomic, strong) UILabel *noLabel;
//图片
@property (nonatomic, strong) UIImageView *icon;
//图片描述
@property (nonatomic, strong) UILabel *descLabel;
//左边按钮
@property (nonatomic, strong) UIButton *leftButton;
//右边按钮
@property (nonatomic, strong) UIButton *rightButton;

//图片索引，index默认是0
@property (nonatomic, assign) int index;

/**设置一个图像的数组*/
//新的注释，可以显式中文
@property (nonatomic, strong) NSArray *imageList;

/*
 @property 
 自动为我们生成 set，get 方法的声明和实现
 带下划线的成员变量
 */
@end

@implementation ViewController

//控件懒加载
//不需要每次都在 viewdidload 里实例化数组，只要在需要的时候实例化即可
//重写 get 方法
- (NSArray *)imageList
{
    //只有第一次调用imageList 的 getter 方法的时候，如果为空，那么再实例化并建立数组，其他时候，直接返回成员变量
    if (_imageList == nil) {
        //使用字典
        NSDictionary *dict1 = @{@"name" : @"biaoqingdi", @"desc" : @"表情"};
        NSDictionary *dict2 = @{@"name" : @"bingli", @"desc" : @"病历"};
        NSDictionary *dict3 = @{@"name" : @"chiniupa", @"desc" : @"吃牛扒"};
        NSDictionary *dict4 = @{@"name" : @"danteng", @"desc" : @"蛋疼"};
        NSDictionary *dict5 = @{@"name" : @"wangba", @"desc" : @"王八"};
        
        self.imageList = @[dict1, dict2, dict3, dict4, dict5];
    }
    
    return _imageList;
}

//初始化工作
//viewDidLoad是视图加载完成后调用的方法，通常在此方法中执行视图控制器的初始化工作
- (void)viewDidLoad {
    [super viewDidLoad];
    //实例化控件
    //1、序号标签的编写
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 20, 320, 40)];
  //  label.text = @"1/5";
    //居中对齐
    label.textAlignment = NSTextAlignmentCenter;
    [self.view addSubview:label];
    //记录改变
    self.noLabel = label;
    
    //2、图片控件
    CGFloat imageW = 200;
    CGFloat imageH = 200;
    CGFloat imageX = (320 - imageW) / 2;
    CGFloat imageY = 80;
    //实例化一个图像视图
    UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(imageX, imageY, imageW, imageH)];
    //实例化一个图像
   // UIImage *image = [UIImage imageNamed:@"biaoqingdi"];
    //把图片显示到imageView
   // imageView.image = image;
    //把图像增加到 view
    [self.view addSubview:imageView];
    //记录下改变
    self.icon = imageView;
    
    //3、图片描述 label 控件
    UILabel *label1 = [[UILabel alloc] initWithFrame:CGRectMake(0, 300, 300, 80)];
   // label1.text = @"发发发";
    //居中对齐
    label1.textAlignment = NSTextAlignmentCenter;
    [self.view addSubview:label1];
    //记录改变
    self.descLabel = label1;
    
    //4、左边的按钮
    UIButton *leftBtn = [[UIButton alloc] init];
    //设置按钮的背景图
    [leftBtn setBackgroundImage:[UIImage imageNamed:@"left_normal"] forState:UIControlStateNormal];
    [leftBtn setBackgroundImage:[UIImage imageNamed:@"left_highlighted"] forState:UIControlStateHighlighted];
    //设置按钮的大小
    leftBtn.frame = CGRectMake(0, 0, 40, 40);
    //设置按钮的位置
    leftBtn.center = CGPointMake(self.icon.frame.origin.x / 2, self.icon.center.y);
    [self.view addSubview:leftBtn];
    //设置监听
    [leftBtn addTarget:self action:@selector(leftClick) forControlEvents:UIControlEventTouchUpInside];
    self.leftButton = leftBtn;
    
    //5、右边的按钮
    UIButton *rightBtn = [[UIButton alloc] init];
    //设置按钮的背景图
    [rightBtn setBackgroundImage:[UIImage imageNamed:@"right_normal"] forState:UIControlStateNormal];
    [rightBtn setBackgroundImage:[UIImage imageNamed:@"right_highlighted"] forState:UIControlStateHighlighted];
    //设置按钮的大小
    rightBtn.frame = CGRectMake(0, 0, 40, 40);
    //设置按钮的位置
    rightBtn.center = CGPointMake(self.view.frame.size.width - self.icon.frame.origin.x / 2, self.icon.center.y);
    
    [self.view addSubview:rightBtn];
    
    //设置监听
    [rightBtn addTarget:self action:@selector(rightClick) forControlEvents:UIControlEventTouchUpInside];
    self.rightButton = rightBtn;
    
    [self change];
}

- (void)change
{
    //更具 self.index 来显示序号标签，图形，，描述
    self.noLabel.text = [NSString stringWithFormat:@"%d / %d", self.index + 1, 5];
    self.icon.image = [UIImage imageNamed:self.imageList[self.index][@"name"]];
    self.descLabel.text = self.imageList[self.index][@"desc"];
    
    self.leftButton.enabled = (self.index != 0);
    self.rightButton.enabled = (self.index != 4);
}

//left
- (void)leftClick
{
    self.index--;
    [self change];
}

//right
- (void)rightClick
{
    self.index++;
    [self change];
}

@end