IOS开发之——图片查看器(18)

一 概述

本文实现一种简单的图片查看器:

  • 显示当前图片和图标描述及当前是第几张
  • 通过左按钮向左切换图片,当前图片是第一张时,按钮灰色不可点击
  • 通过右按钮向右切换图片,当图片是最后一张时,按钮灰色不可点击

二 效果图

三 代码

3.1 OC模式下(ViewController.m)

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#import "ViewController.h"

@interface ViewController ()
//控件
@property (nonatomic,strong) UILabel *noLabel;
@property (nonatomic,strong) UIImageView *iconImage;
@property (nonatomic,strong) UILabel *descLabel;
@property (nonatomic,strong) UIButton *leftButton;
@property (nonatomic, strong) UIButton *rightButton;

//当前照片的索引
@property (nonatomic,assign) int index;
//图片信息的数组
@property (nonatomic,strong) NSArray *imageList;
@end
@implementation ViewController

//懒加载,给图片复制
- (NSArray *)imageList
{
NSLog(@"读取图像信息");
if (_imageList == nil) {
NSLog(@"实例化数组");

// "包" Bundle [NSBundle mainBundle]编译安装之后对应的程序包
NSString *path = [[NSBundle mainBundle] pathForResource:@"ImageList" ofType:@"plist"];
NSLog(@"%@", path);

// 在OC中ContentsOfFile,通常需要完整的路径
_imageList = [NSArray arrayWithContentsOfFile:path];
NSLog(@"%@", _imageList);
}
return _imageList;
}

//noLabel
- (UILabel *)noLabel
{
if (_noLabel==nil)
{
UILabel *label=[[UILabel alloc]initWithFrame:CGRectMake(0, 20, self.view.bounds.size.width, 40)];
_noLabel=label;
_noLabel.textAlignment=NSTextAlignmentCenter;
[self.view addSubview:_noLabel];
}
return _noLabel;
}

//iconImage
- (UIImageView *)iconImage
{
if (_iconImage==nil) {
CGFloat imageW=200;
CGFloat imageH=200;
CGFloat imageX=(self.view.bounds.size.width-imageW)*0.5;
CGFloat imageY=CGRectGetMaxY(self.noLabel.frame)+20;
_iconImage= [[UIImageView alloc] initWithFrame:CGRectMake(imageX, imageY, imageW, imageH)];
[self.view addSubview:_iconImage];
}
return _iconImage;
}

//dessLabel
- (UILabel *)descLabel
{
if (_descLabel == nil) {
CGFloat descY = CGRectGetMaxY(self.iconImage.frame);
_descLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, descY, self.view.bounds.size.width, 100)];
_descLabel.textAlignment = NSTextAlignmentCenter;

// 需要Label具有“足够的高度”,不限制显示的行数
_descLabel.numberOfLines = 0;
[self.view addSubview:_descLabel];
}
return _descLabel;
}
- (UIButton *)leftButton
{
if (_leftButton == nil) {
_leftButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 40, 40)];
CGFloat centerY = self.iconImage.center.y;
CGFloat centerX = self.iconImage.frame.origin.x * 0.5;
_leftButton.center = CGPointMake(centerX, centerY);

[_leftButton setBackgroundImage:[UIImage imageNamed:@"left_normal"] forState:UIControlStateNormal];
[_leftButton setBackgroundImage:[UIImage imageNamed:@"left_highlighted"] forState:UIControlStateHighlighted];
[self.view addSubview:_leftButton];

_leftButton.tag = -1;

[_leftButton addTarget:self action:@selector(clickButton:) forControlEvents:UIControlEventTouchUpInside];
}
return _leftButton;
}

- (UIButton *)rightButton
{
if (_rightButton == nil) {
_rightButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 40, 40)];
CGFloat centerY = self.iconImage.center.y;
CGFloat centerX = self.iconImage.frame.origin.x * 0.5;
_rightButton.center = CGPointMake(self.view.bounds.size.width - centerX, centerY);

[_rightButton setBackgroundImage:[UIImage imageNamed:@"right_normal"] forState:UIControlStateNormal];
[_rightButton setBackgroundImage:[UIImage imageNamed:@"right_highlighted"] forState:UIControlStateHighlighted];
[self.view addSubview:_rightButton];

_rightButton.tag = 1;

[_rightButton addTarget:self action:@selector(clickButton:) forControlEvents:UIControlEventTouchUpInside];
}
return _rightButton;
}

/** 在viewDidLoad创建界面 */
- (void)viewDidLoad
{
[super viewDidLoad];

// [self.view addSubview:self.noLabel];

// 显示照片信息
[self showPhotoInfo];
}

- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
}

/**
重构的目的:让相同的代码只出现一次
*/
- (void)showPhotoInfo
{
// 设置序号
self.noLabel.text = [NSString stringWithFormat:@"%d/%d", self.index + 1, 5];

// 效率不高,每次都会生成数组
// 如何解决?使用属性记录字典数组
// NSDictionary *dict1 = @{@"name": @"biaoqingdi", @"desc": @"表情1"};
// NSDictionary *dict2 = @{@"name": @"bingli", @"desc": @"病例1"};
// NSDictionary *dict3 = @{@"name": @"chiniupa", @"desc": @"吃牛扒1"};
// NSDictionary *dict4 = @{@"name": @"danteng", @"desc": @"蛋疼1"};
// NSDictionary *dict5 = @{@"name": @"wangba", @"desc": @"网吧1"};
// NSArray *array = @[dict1, dict2, dict3, dict4, dict5];

// 设置图像和描述
self.iconImage.image = [UIImage imageNamed:self.imageList[self.index][@"name"]];
self.descLabel.text = self.imageList[self.index][@"desc"];

self.rightButton.enabled = (self.index != 4);
self.leftButton.enabled = (self.index != 0);
}

// 在OC中,很多方法的第一个参数,都是触发该方法的对象!
- (void)clickButton:(UIButton *)button
{
// 根据按钮调整当前显示图片的索引?
self.index += button.tag;

[self showPhotoInfo];
}
@end