Question

这可能是一个简单的问题，但我已经搜索了几个小时试图找出它。

最初我试图创建一个允许我通过左右滑动来更改背景图像的视图。在无法找到任何简单的方法之后，我想我可以用一组图像制作一个数组，并将背景图像设置为该数组中的特定对象。我已经成功地设置了它，但是我无法弄清楚如何使用手势来改变索引处对象的值。我正在想象currentImage ++或currentImage --的某些内容来改变价值，但我不知道如何实现它。

如果有人知道怎么做，请帮忙。或者，如果有人有更有效的方法来做到这一点，我也想听。我是iOS编程的新手。

这是viewDidLoad。

中的内容

UIImage *beachImage = [UIImage imageNamed:@"Malibu_Sunset_1.jpg"];
UIImage *cityImage = [UIImage imageNamed:@"chicago_marina_city_parking_garages.jpg"];
UIImage *lodgeImage = [UIImage imageNamed:@"ski_lodge.jpg"];
UIImage *airplaneImage = [UIImage imageNamed:@"airplanes-work-1.jpg"];
UIImage *farmImage = [UIImage imageNamed:@"ideal-farm-house-photo.jpg"];

NSMutableArray *vacationImages = [NSMutableArray arrayWithObjects: airplaneImage, beachImage, cityImage, lodgeImage, farmImage, nil];

int numberOfImages = [vacationImages count];
int currentValue = 0;
UIImage *currentImage = [vacationImages objectAtIndex:currentValue];

self.mainViewImage.image = currentImage;



for (UIImage *currentImage in vacationImages) {
    UIImageView *line = [[UIImageView alloc] initWithImage:currentImage];
    line.hidden = YES;
    line.tag = currentValue;
    [self.view addSubview:line];
    numberOfImages++;
}

UISwipeGestureRecognizer *leftRecognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFromLeft)];
[leftRecognizer setDirection: UISwipeGestureRecognizerDirectionLeft];
[[self view] addGestureRecognizer:leftRecognizer];


UISwipeGestureRecognizer *rightRecognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFromRight)];
[rightRecognizer setDirection: UISwipeGestureRecognizerDirectionRight];
[[self view] addGestureRecognizer:rightRecognizer];

Answer 1

您不必添加5个UIImageViews，只需添加一个并更改其图像：

in .h:
UIImageView *bgImageView;
NSArray *vacationImages;
int currentImageIndex;

in .m
-(void) handleSwipeFromLeft
{
     currentImageIndex--;
     if(currentImageIndex< 0)
         currentImageIndex= vacationImages.count;

     NSString *imageName = [vacationImages objectAtIndex:currentImageIndex];
     bgImageView.image = [UIImage imageNamed:imageName];
}

-(void) handleSwipeFromRight
{
     currentImageIndex++;
     if(currentImageIndex>= vacationImages.count)
         currentImageIndex= 0;

     NSString *imageName = [vacationImages objectAtIndex:currentImageIndex];
     bgImageView.image = [UIImage imageNamed:imageName];
}

Answer 2

使用您自己的代码：

in .m

#import "ViewController.h"

@interface ViewController ()

@property (nonatomic, strong) UIImageView *mainViewImage;
@property (nonatomic) int currentValue;
@property (nonatomic, strong) NSArray *vacationImages;

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    // change the size of the frame of the image here
    self.mainViewImage = [[UIImageView alloc]initWithFrame:CGRectMake(0, 40, 320, 200)];
    [self.view addSubview:self.mainViewImage];

    UIImage *beachImage = [UIImage imageNamed:@"Malibu_Sunset_1.jpg"];
    UIImage *cityImage = [UIImage imageNamed:@"chicago_marina_city_parking_garages.jpg"];
    UIImage *lodgeImage = [UIImage imageNamed:@"ski_lodge.jpg"];
    UIImage *airplaneImage = [UIImage imageNamed:@"airplanes-work-1.jpg"];
    UIImage *farmImage = [UIImage imageNamed:@"ideal-farm-house-photo.jpg"];

    self.vacationImages = [NSArray arrayWithObjects: airplaneImage, beachImage, cityImage, lodgeImage, farmImage, nil];

    self.currentValue = 0;

    UIImage *currentImage = [self.vacationImages objectAtIndex:self.currentValue];
    self.mainViewImage.image = currentImage;

    UISwipeGestureRecognizer *leftRecognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFromLeft: )];
    [leftRecognizer setDirection: UISwipeGestureRecognizerDirectionLeft];
    [[self view] addGestureRecognizer:leftRecognizer];

    UISwipeGestureRecognizer *rightRecognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFromRight:)];
    [rightRecognizer setDirection: UISwipeGestureRecognizerDirectionRight];
    [[self view] addGestureRecognizer:rightRecognizer];
}

- (void) handleSwipeFromLeft: (id) sender
{
    if (self.currentValue == 0)
    {
        self.currentValue = 4;
    }
    else
    {
        self.currentValue--;
    }

    UIImage *currentImage = [self.vacationImages objectAtIndex:self.currentValue];
    self.mainViewImage.image = currentImage;
}

- (void) handleSwipeFromRight: (id) sender
{
    if (self.currentValue == 4)
    {
        self.currentValue = 0;
    }
    else
    {
        self.currentValue++;
    }

    UIImage *currentImage = [self.vacationImages objectAtIndex:self.currentValue];
    self.mainViewImage.image = currentImage;
}

@end

如何使用按钮/手势来更改值？ - iOS

2 个答案: