根据 UIPanGestureRecognizer 翻译值更改 UIImageView 中的图像

Posted 2023-03-16

【中文标题】根据 UIPanGestureRecognizer 翻译值更改 UIImageView 中的图像

【英文标题】：Change image in UIImageView based on UIPanGestureRecognizer translation value

【发布时间】：2012-12-14 15:02:34

【问题描述】：

我在数组中有 8 张图像，UIImageView 一次显示数组中的一张图像。我在UIImageView 上也有UIPanGestureRecognizer，所以当用户在图像上横向移动手指时，它会改变（有点像图像顶部的隐形滚动条）。我正在使用平移手势的平移值来更改图像。这一切都有效，但不是我想要的方式。图像变化太快，只需短手指平移即可滚动图像。有没有办法需要更长的平移来更改图像？或者任何其他方法可以让用户“更顺畅”？

.h

@interface FirstViewController : UIViewController
    @property (nonatomic, retain) IBOutlet UIImageView *imageView;
    - (IBAction)pan:(UIGestureRecognizer *)panGesture;

.m

@interface FirstViewController () 
    NSArray * imageArray;
    int _currentIndex;


@end

@implementation FirstViewController

- (IBAction)pan:(UIPanGestureRecognizer *)panGesture 
  //  NSLog(@"panned");
    CGPoint translation = [panGesture translationInView:self.view];
    [self.panLabel setText: NSStringFromCGPoint(translation)];
    NSLog(@"%@ translation", NSStringFromCGPoint(translation));

    if (translation.x<-1) 
        _currentIndex=(_currentIndex<=0)?0:_currentIndex-1;
        UIImage *img = [UIImage imageNamed:[imageArray objectAtIndex:_currentIndex]];
        [self.imageView setImage:img];
    
    else if(translation.x>1)
        _currentIndex=(_currentIndex>=7)?7:_currentIndex+1;
        UIImage *img = [UIImage imageNamed:[imageArray objectAtIndex:_currentIndex]];
        [self.imageView setImage:img];
    
    [panGesture setTranslation:CGPointZero inView:self.view];


- (void)viewDidLoad 
    [super viewDidLoad];
    imageArray = [[NSArray alloc]
                  initWithObjects:@"image1.jpg", @"image2.jpg", @"image3.jpg", @"image4.jpg", @"image5.jpg", @"image6.jpg", @"image7.jpg", @"image8.jpg", nil];

【参考方案1】：

您可以修改代码以跟踪 X 平移随着时间的推移。这将允许您为您的锅量设置一个变量。修改后的代码如下：

@interface FirstViewController () 
    NSArray * imageArray;
    int _currentIndex;

    CGFloat _currentPanXAmount;
    CGFloat _panThreshold;


@end

@implementation FirstViewController

- (IBAction)pan:(UIPanGestureRecognizer *)panGesture 
    CGPoint translation = [panGesture translationInView:self.view];

    _currentPanXAmount += translation.x;

    [self.panLabel setText: NSStringFromCGPoint(translation)];
    NSLog(@"%@ translation", NSStringFromCGPoint(translation));

    if (_currentPanXAmount < (-1 * _panThreshold)) 
        _currentIndex=(_currentIndex<=0)?0:_currentIndex-1;
        UIImage *img = [UIImage imageNamed:[imageArray objectAtIndex:_currentIndex]];
        [self.imageView setImage:img];
        _currentPanXAmount = 0.0;
    
    else if(_currentPanXAmount > _panThreshold)
        _currentIndex=(_currentIndex>=7)?7:_currentIndex+1;
        UIImage *img = [UIImage imageNamed:[imageArray objectAtIndex:_currentIndex]];
        [self.imageView setImage:img];
        _currentPanXAmount = 0.0;
    
    [panGesture setTranslation:CGPointZero inView:self.view];


- (void)viewDidLoad 
    [super viewDidLoad];
    imageArray = [[NSArray alloc]
                  initWithObjects:@"image1.jpg", @"image2.jpg", @"image3.jpg", @"image4.jpg", @"image5.jpg", @"image6.jpg", @"image7.jpg", @"image8.jpg", nil];

    // Make this larger for slower transitions and smaller for faster transitions.
    _panThreshold = 10.0;

【讨论】：

这正是我想要实现的。非常感谢！

关于图像前进的方向：从右到左平移时，您从 8 ---> 1 开始。必须颠倒“if 语句”才能有更直观的“滚动”。你还缺少一个括号，现在我正在编辑它。

@robhasacamera _currentIndex=(_currentIndex>=7)?7:_currentIndex+1;你怎么翻译这是swift2？