物镜c捏放大后如何删除顶部和底部空间？

Question

My problem with after pinch zoom, when I pinch zoom and after drag image then white space on top and bottom.

My Code as per apple documentation.

https://developer.apple.com/library/content/documentation/WindowsViews/Conceptual/UIScrollView_pg/ZoomZoom/ZoomZoom.html

Sample code

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    scrollView.minimumZoomScale=0.5;
    scrollView.maximumZoomScale=6.0;
    scrollView.contentSize=CGSizeMake(1280, 960);
    scrollView.delegate = self;
}
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    return imageView;
}

Thank you.

Answer 1

At first set your minimum zoom scale to 1.0:

    scrollView.minimumZoomScale = 1.0;

Next, set the contentSize for scrollView:

    scrollView.contentSize = [UIScreen mainScreen].bounds.size;

And if you don't want to see the extra space when bouncing, add the next line:

    scrollView.bounces = NO;

Completely, the method should looks something like this:

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.scrollView.minimumZoomScale = 1.0;
    self.scrollView.maximumZoomScale = 6.0;

    self.scrollView.bounces     = NO;
    self.scrollView.contentSize = [UIScreen mainScreen].bounds.size;
    self.scrollView.delegate    = self;
}

Hope it will help.

Answer 2

This is how I do it. If you image fits perfectly into the view, there will be no white space when you zoom and pan.

If your image does not fit or scale properly, there will be white space on the sides OR the top.

First make sure your image is the correct size. Next you need to add minimumZoomScale and maximumZoomScale to the scrollView. The rest will work after that. You can use auto-layout or frames. Up to you.

This example uses auto-layout:

#import "ViewController.h"

@interface AutoLayoutScrollView : UIScrollView
@property (nonatomic, weak) UIView *contentView;
@end

@implementation AutoLayoutScrollView
- (instancetype)init {
    if (self = [super init]) {
        UIView *view = [[UIView alloc] init];
        self.contentView = view;

        [self addSubview:view];
        [self.contentView.leftAnchor constraintEqualToAnchor:self.leftAnchor].active = YES;
        [self.contentView.rightAnchor constraintEqualToAnchor:self.rightAnchor].active = YES;
        [self.contentView.topAnchor constraintEqualToAnchor:self.topAnchor].active = YES;
        [self.contentView.bottomAnchor constraintEqualToAnchor:self.bottomAnchor].active = YES;
        [self.contentView setTranslatesAutoresizingMaskIntoConstraints:NO];
    }

    return self;
}

- (void)didMoveToSuperview {
    [super didMoveToSuperview];

    UIView *parent = self.superview;

    if (parent) {
        [self.leftAnchor constraintEqualToAnchor:parent.leftAnchor].active = YES;
        [self.rightAnchor constraintEqualToAnchor:parent.rightAnchor].active = YES;
        [self.topAnchor constraintEqualToAnchor:parent.topAnchor].active = YES;
        [self.bottomAnchor constraintEqualToAnchor:parent.bottomAnchor].active = YES;
        [self setTranslatesAutoresizingMaskIntoConstraints:NO];
    }
}
@end


@interface ViewController () <UIScrollViewDelegate>
@property (nonatomic, strong) AutoLayoutScrollView *scrollView;
@property (nonatomic, strong) UIImageView *imageView;
@property (nonatomic, strong) UIPanGestureRecognizer *panGesture;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    self.scrollView = [[AutoLayoutScrollView alloc] init];
    [self.view addSubview:self.scrollView];
    [self.scrollView.contentView.widthAnchor constraintEqualToAnchor:self.view.widthAnchor].active = YES;
    [self.scrollView.contentView.heightAnchor constraintEqualToAnchor:self.view.heightAnchor].active = YES;

    self.imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Image"]];
    [self.imageView setContentMode:UIViewContentModeScaleAspectFit];

    [self.scrollView.contentView addSubview:self.imageView];
    [self.imageView.leftAnchor constraintEqualToAnchor:self.scrollView.contentView.leftAnchor].active = YES;
    [self.imageView.rightAnchor constraintEqualToAnchor:self.scrollView.contentView.rightAnchor].active = YES;
    [self.imageView.topAnchor constraintEqualToAnchor:self.scrollView.contentView.topAnchor].active = YES;
    [self.imageView.bottomAnchor constraintEqualToAnchor:self.scrollView.contentView.bottomAnchor].active = YES;
    [self.imageView setTranslatesAutoresizingMaskIntoConstraints:NO];

    [self.scrollView setMinimumZoomScale:1.0];
    [self.scrollView setMaximumZoomScale:3.0];
    [self.scrollView setZoomScale:1.0f animated:YES];
    [self.scrollView setDelegate:self];
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
    return self.imageView;
}
@end