iOS开发之图片查看器

来源：互联网发布：有了阿里云ems如何建站编辑：程序博客网时间：2024/05/21 11:08

可以学到UIButton，UIImageView，UILabel的代码创建。实现一个简单的点击按钮，切换图片的小程序。

知识点：

在getter方法中，不要使用self.imageList(会调用imageList的getter方法)，应该使用_imageList，否则会死循环

self.noLabel.textAlignment = NSTextAlignmentCenter; // 居中对齐CGFloat imageY = CGRectGetMaxY(self.noLabel.frame) + 20;   // 取出noLabel的最大Y值，一定用frame，不能用bounds

plist资源的使用

NSString *path = [[NSBundle mainBundle] pathForResource:@"ImageList" ofType:@"plist"];NSLog(@"%@", path);// 需要完整的路径_imageList = [NSArray arrayWithContentsOfFile:path];

在OC中

1.如果对象没有强引用，会被立即释放

2.默认的对象，都是强引用的。

__weak Person *p = [[Person alloc] init];// 声明一个弱引用对象

git:https://git.oschina.net/taylordavid/ImageSeeker.git

部分代码展示：

#import "ViewController.h"@interface ViewController ()@property (nonatomic, strong) UILabel *noLabel;         // 序号@property (nonatomic, strong) UIImageView *iconImage;   // 图片@property (nonatomic, strong) UILabel *descLabel;       // 描述@property (nonatomic, strong) UIButton *leftButton;     // 上一张@property (nonatomic, strong) UIButton *rightButton;    // 下一张@property (nonatomic, assign) int index;                // 当前显示的照片索引@property (nonatomic, strong) NSArray *imageList;       // 信息@end@implementation ViewController#pragma mark - 懒加载- (NSArray *)imageList {    if (_imageList == nil) {                NSString *path = [[NSBundle mainBundle] pathForResource:@"ImageList" ofType:@"plist"];        NSLog(@"%@", path);        // 需要完整的路径        _imageList = [NSArray arrayWithContentsOfFile:path];        NSLog(@"%@", _imageList);    }        return _imageList;}- (UILabel *)noLabel {    if (_noLabel == nil) {        _noLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 20, self.view.bounds.size.width, 40)];        _noLabel.textAlignment = NSTextAlignmentCenter; // 居中对齐        [self.view addSubview:_noLabel];    }        return _noLabel;}- (UIImageView *)iconImage {    if (_iconImage == nil) {        CGFloat imageWidth = 200;        CGFloat imageHeight = 200;        CGFloat imageX = (self.view.bounds.size.width - imageWidth) * 0.5;        CGFloat imageY = CGRectGetMaxY(self.noLabel.frame) + 20;   // 取出noLabel的最大Y值，一定用frame，不能用bounds                _iconImage = [[UIImageView alloc] initWithFrame:CGRectMake(imageX, imageY, imageWidth, imageHeight)];        _iconImage.backgroundColor = [UIColor redColor];        [self.view addSubview:_iconImage];    }        return _iconImage;}- (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;        _descLabel.numberOfLines = 0; // 不限制行数，但是保证label有足够的空间，高度大于行所占的总高度就好s        [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];        [_leftButton addTarget:self action:@selector(clickButton:) forControlEvents:UIControlEventTouchUpInside]; // 在OC中，很多方法的第一个参数都是触发该方法的对象，这里是self        _leftButton.tag = -1;   // 设置tag        [self.view addSubview:_leftButton];    }        return _leftButton;}- (UIButton *)rightButton {    if (_rightButton == nil) {        _rightButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 40, 40)];        _rightButton.center = CGPointMake(self.view.bounds.size.width - self.leftButton.center.x, self.leftButton.center.y);        [_rightButton setBackgroundImage:[UIImage imageNamed:@"right_normal"] forState:UIControlStateNormal];        [_rightButton setBackgroundImage:[UIImage imageNamed:@"right_highlighted"] forState:UIControlStateHighlighted];        // 添加监听事件        [_rightButton addTarget:self action:@selector(clickButton:) forControlEvents:UIControlEventTouchUpInside];        _rightButton.tag = 1;        [self.view addSubview:_rightButton];    }        return _rightButton;}// 视图加载完后执行该函数- (void)viewDidLoad {    [super viewDidLoad];        [self showPhotoInfo];}/* 显示图片 */- (void)showPhotoInfo {    self.noLabel.text = [NSString stringWithFormat:@"%d/%d", self.index + 1, 5];    // 设置序号        self.iconImage.image = [UIImage imageNamed:self.imageList[self.index][@"name"]];    self.descLabel.text = self.imageList[self.index][@"desc"];        // 控制按钮状态    self.rightButton.enabled = (self.index != 4);    self.leftButton.enabled = (self.index != 0);}- (void)clickButton:(UIButton *)button {    // 根据按钮调整当前显示图片的索引    self.index += button.tag; // 这里通过设置特殊的tag实现的，挺巧妙        [self showPhotoInfo];}@end

效果展示：

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