iOS-UIScrollView-图片缩放

一. 实现功能

两个手指捏合,可以放大或者缩小图片.

二.原理说明

1. 实现缩放功能的四个步骤

(1) 让控制器遵守代理协议

(2) 让scrollView设置代理 self

(3) 调用代理方法, 返回需要实现缩放的子控件

(4) 设置缩放比例

2.补充: 跟缩放相关的代理方法

(1)  - (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view

(2)  - (void)scrollViewDidZoom:(UIScrollView *)scrollView

三. 代码部分 (可以直接复制使用)

#import "ThirdViewController.h"

#import "Masonry.h"

@interface ThirdViewController () <UIScrollViewDelegate>

@property (nonatomic, strong) UIScrollView  * scrollView;

@property (nonatomic, strong) UIImage       * image;

@property (nonatomic, strong) UIImageView   * imageView;

@end

@implementation ThirdViewController

#pragma mark - 生命周期

#pragma mark viewDidLoad

- (void)viewDidLoad

{

    [super viewDidLoad];

    [self basicSetting];

    [self addscrollView];

    [self addImageView];

}

#pragma mark - 系统代理

#pragma mark 返回需要缩放的子控件

-  (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView

{

    return self.imageView;

}

#pragma mark - 实现方法

#pragma mark 基本设置

- (void)basicSetting

{

    self.title = @"UIScrollView-图片放大";

}

- (void)addscrollView

{

    [self.view addSubview:self.scrollView];

    [self.scrollView mas_makeConstraints:^(MASConstraintMaker *make) {

        make.edges.mas_equalTo(self.view).with.insets(UIEdgeInsetsMake(, , , ));

    }];

}

- (void)addImageView

{

    [self.scrollView addSubview:self.imageView];

    [self.imageView mas_makeConstraints:^(MASConstraintMaker *make) {

        make.left.mas_equalTo(self.scrollView);

        make.width.mas_equalTo(self.view.bounds.size.width);

        make.top.mas_equalTo(self.scrollView);

        make.height.mas_equalTo([UIScreen mainScreen].bounds.size.height);

    }];

}

#pragma mark - setter & getter

- (UIScrollView *)scrollView

{

    if (!_scrollView)

    {

        self.scrollView = [[UIScrollView alloc] init];

        self.scrollView.backgroundColor = [UIColor orangeColor];

        // 设置最大拉伸比例

        self.scrollView.maximumZoomScale = 2.0f;

        // 设置最小缩放比例

        self.scrollView.minimumZoomScale = 0.5f;

        // 设置scrollview 的滚动范围和图片真实尺寸一致

        self.scrollView.contentSize = self.image.size;

        self.scrollView.delegate = self;

    }

    return _scrollView;

}

- (UIImage *)image

{

    if (!_image)

    {

        self.image = [UIImage imageNamed:@"红妹子"];

    }

    return _image;

}

- (UIImageView *)imageView

{

    if (!_imageView)

    {

        self.imageView = [[UIImageView alloc] init];

        self.imageView.image = self.image;

    }

    return _imageView;

}

@end

iOS-UIScrollView-图片缩放的相关教程结束。