从静止的 UIImageView 或按钮中拖出新的 UIImageView 对象

Question

我是iOS开发的初学者，我正在为我的学校做一个副项目。我想做的是有一个小图像，用户可以从中拖出更多图像。从本质上讲，我有一个生成正方形的应用程序，我需要有一个设置的正方形，用户可以在其中触摸正方形并将新正方形拖到板上。我已经在一定程度上实现了这一目标，但还不是所需的行为。目前，用户必须触摸按钮，然后松开，然后才能与新方块交互以将其拖离按钮。我想要的是以某种方式将触摸事件传递给创建的新 UIImageView 对象，以便无缝拖出一个新方块。下面是我当前的代码。

//UIViewController 
#import <UIKit/UIKit.h>
#import "Tile.h"
@interface MenuViewController : UIViewController
{
    Tile *tileObject;
}
@end
#import "MenuViewController.h"
@implementation MenuViewController
- (IBAction)createTile:(UIButton *)sender {
    CGFloat tileX = sender.center.x;
    CGFloat tileY = sender.center.y;
    tileObject = [[Tile alloc]initWithX:tileX andY:tileY];
    [self.view addSubview:tileObject];
}
- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Release any cached data, images, etc that aren't in use.
}
#pragma mark - View lifecycle
- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}
- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    // Return YES for supported orientations
    return YES;
}
@end


//Custom Tile Class
#import <UIKit/UIKit.h>
@interface Tile : UIImageView
{
    CGPoint startLocation; 
}
- (id)init; //Default Initialization
- (id)initWithX:(CGFloat)x andY:(CGFloat)y; //Initialization with coordinate points from single screen tap
@end
#import "Tile.h"
@implementation Tile
//Default initialization
-(id) init 
{
    self = [self initWithX:0 andY:0];
    return self;
}
//Initialization with coordinate points from single screen tap
- (id)initWithX:(CGFloat)centerX andY:(CGFloat)centerY
{
    //Creates a UIImageView object from an image file
    UIImage *image = [UIImage imageNamed:@"redblock.png"];
    self = [super initWithImage:image];
    //Used to center the image under the single screen tap
    centerX -= (image.size.height/2);
    centerY -= (image.size.height/2);
    //Sets the position of the image
    self.frame = CGRectMake(centerX, centerY, image.size.width, image.size.height);
    self.userInteractionEnabled = YES; //required for interacting with UIImageViews
    return self;
}
/* Methods from Stack Overflow
http://stackoverflow.com/questions/1991899/uiimage-detecting-touch-and-dragging
Referenced from http://www.iphoneexamples.com/
*/
- (void) touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event {
    // Retrieve the touch point
    CGPoint point = [[touches anyObject] locationInView:self];
    startLocation = point;
    [[self superview] bringSubviewToFront:self];
}
- (void) touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event {
    // Move relative to the original touch point
    CGPoint point = [[touches anyObject] locationInView:self];
    CGRect frame = [self frame];
    frame.origin.x += point.x - startLocation.x;
    frame.origin.y += point.y - startLocation.y;
    [self setFrame:frame];
}
/* 
end of methods from Stack Overflow
*/
@end

Answer 1

如果初始触摸点可以是图像视图，其中要拖动的图像作为其图像，那么您可以这样做：

在你的menuViewController类中，把它放在viewDidLoad中（并删除按钮及其方法）：

- (void)viewDidLoad
{
    [super viewDidLoad];
    tileObject = [[Tile alloc]initWithX:160 andY:200];
    [self.view addSubview:tileObject];
}

然后在 Tile 类中，在 touchesBestarted：withEvent： 方法中创建一个新磁贴，并像以前一样执行拖动：

- (void) touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event {
    Tile *newTile = [[Tile alloc]initWithX:160 andY:200];
    [self.superview addSubview:newTile];
    // Retrieve the touch point
    CGPoint point = [[touches anyObject] locationInView:self];
    startLocation = point;
    [[self superview] bringSubviewToFront:self];
}

Answer 2

您需要执行以下操作，而不是使用带有 touchDown 事件的按钮：

1） 检测触摸开始并创建您的磁贴

2） 检测触摸移动并移动您的磁贴