Simulator Screen Shot - iPhone 8 Plus - 2018-08-09 at 09.43.43.png

.h

#import <UIKit/UIKit.h>

@interface CutImageViewControllerUNF : UIViewController

@property (nonatomic, strong) NSDictionary *imageInfoDict;
@end

.m

#import "CutImageViewControllerUNF.h"

#define kWidth            ([UIScreen mainScreen].bounds.size.width * 1.0)
#define kHeight           ([UIScreen mainScreen].bounds.size.height * 1.0)
#define kCropWidth     (300.f)

@interface CutImageViewControllerUNF () <UIScrollViewDelegate>

@property (nonatomic, strong) UIScrollView *scrollView;
@property (nonatomic, strong) UIImage *originImg;
@end

@implementation CutImageViewControllerUNF

- (void)viewDidLoad {
    [super viewDidLoad];
    [self.view setBackgroundColor:[UIColor  blackColor]];
    [self.view addSubview:self.scrollView];
    [self imageview];
    [self userInterface];
}

- (void)viewDidLayoutSubviews {
    [super viewDidLayoutSubviews];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

#pragma mark -
- (void)imageview {
    CGSize imgSize   = [self imageSize];
    CGPoint point    = CGPointMake((kWidth - kCropWidth)/2.f, (kHeight - kCropWidth)/2.f - 64.f);
    
    UIImageView *imageview = [[UIImageView alloc] initWithImage:self.originImg];
    imageview.frame  = CGRectMake(point.x, point.y, imgSize.width, imgSize.height);
    self.scrollView.contentSize = CGSizeMake(imgSize.width + (point.x)*2.f, imgSize.height + (point.y)*2.f);
    self.scrollView.contentOffset = CGPointMake((self.scrollView.contentSize.width)/2.f - kWidth/2.0, (self.scrollView.contentSize.height)/2.f - kHeight/2.0 + 64);
    [self.scrollView addSubview:imageview];
}

- (CGSize)imageSize {
    
    CGSize imgOriginSize = self.originImg.size;
    CGSize imgNewSize = CGSizeZero;
    if (imgOriginSize.width/kWidth < imgOriginSize.height/kHeight) {
        imgNewSize = CGSizeMake(kHeight/imgOriginSize.height*imgOriginSize.width, kHeight);
    } else {
        imgNewSize = CGSizeMake(kWidth, kWidth/imgOriginSize.width*imgOriginSize.height);
    }
    
    if (imgNewSize.width/kCropWidth < 1) {
        imgNewSize = CGSizeMake(imgNewSize.width * (kCropWidth/imgNewSize.width), imgNewSize.height * (kCropWidth/imgNewSize.width));
    }
    
    if (imgNewSize.height/kCropWidth < 1) {
        imgNewSize = CGSizeMake(imgNewSize.width * (kCropWidth/imgNewSize.height), imgNewSize.height * (kCropWidth/imgNewSize.height));
    }
    
    return imgNewSize;
}

#pragma mark -
- (void)userInterface {
    CGPoint point    = CGPointMake(kWidth/2.0 - 150, kHeight/2.0 - 150);
    CGRect cropframe = CGRectMake(point.x, point.y, 300, 300);
    
    UIBezierPath * path = [UIBezierPath bezierPathWithRoundedRect:self.view.bounds cornerRadius:0];
    UIBezierPath * cropPath = [UIBezierPath bezierPathWithRoundedRect:cropframe cornerRadius:0];
    if (YES) {
        cropPath = [UIBezierPath bezierPathWithOvalInRect:cropframe];
    }
    [path appendPath:cropPath];
    
    CAShapeLayer * layer = [[CAShapeLayer alloc] init];
    layer.fillColor = [UIColor colorWithRed:.0 green:.0 blue:.0 alpha:0.5].CGColor;
    //填充规则
    layer.fillRule=kCAFillRuleEvenOdd;
    layer.path = path.CGPath;
    [self.view.layer addSublayer:layer];
}

#pragma mark - UIScrollViewDelegate
- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
    [self  centerContent];
}

- (void)centerContent {
    for (UIView *imageview in self.scrollView.subviews) {
        if ([imageview isKindOfClass:[UIImageView class]]) {
            CGRect imageViewFrame = imageview.frame;
            CGRect scrollBounds = CGRectMake(0, 0, kWidth, kHeight);
            if (imageViewFrame.size.height > scrollBounds.size.height) {
                imageViewFrame.origin.y = kHeight/2.f -150.f - 64.f;
            }else {
                imageViewFrame.origin.y = kHeight/2.f -150.f - 64.f;//(scrollBounds.size.height - imageViewFrame.size.height) / 2.0;
            }
            if (imageViewFrame.size.width < scrollBounds.size.width) {
                imageViewFrame.origin.x = (scrollBounds.size.width - imageViewFrame.size.width) /2.f;
            }else {
                imageViewFrame.origin.x = kWidth/2.f - 150.f;
            }
            imageview.frame = imageViewFrame;
            self.scrollView.contentSize = CGSizeMake(imageViewFrame.size.width + (kWidth/2.0 -150.f)*2.f, imageViewFrame.size.height +  (kHeight/2.f - 150.f - 64.f)*2.f +64.f);
        }
    }
}

- (nullable UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
    for (UIView *imageview in self.scrollView.subviews) {
        if ([imageview isKindOfClass:[UIImageView class]]) {
            return imageview;
        }
    }
    return nil;
}

#pragma mark - Lazying
- (UIScrollView *)scrollView {
    if (!_scrollView) {
        _scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, kWidth, kHeight)];
        _scrollView.showsHorizontalScrollIndicator = NO;
        _scrollView.showsVerticalScrollIndicator   = NO;
        _scrollView.zoomScale = 3.0;
        _scrollView.bouncesZoom = YES;
        _scrollView.minimumZoomScale = 1.0;
        _scrollView.maximumZoomScale = 3.0;
        _scrollView.delegate = self;
    }
   return _scrollView;
}

- (void)setImageInfoDict:(NSDictionary *)imageInfoDict {
    _imageInfoDict = imageInfoDict;
    UIImage *sourceImage = [imageInfoDict objectForKey:UIImagePickerControllerOriginalImage];
    self.originImg = sourceImage;
}

@end

```![Simulator Screen Shot - iPhone 8 Plus - 2018-08-09 at 09.43.43.png](https://upload-images.jianshu.io/upload_images/678464-d3abffb686a8817a.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)