iOS如何實現長按拖動控件

　　實現控件拖動的方法有多種，能夠使用UICollectionView的代理方法直接實現，可是有些開發者在初始時沒有使用UICollectionView建立九宮格，後來增長需求，卻要增長這種拖動移動的效果，又不想更改頁面的初始控件，那麼應該怎麼實現呢？

　　方法很簡單，首先在@interface建立如下全局變量；

@interface YRViewController ()
{
    BOOL contain;
     CGPoint startPoint;
     CGPoint originPoint;
   
}
@property (strong , nonatomic) NSMutableArray *itemArray;
@end

　　如圖所示，在viewDidLoad裏建立了以下的控件佈局；

 1 - (void)viewDidLoad
 2 {
 3     [super viewDidLoad];
 4     
 5     for (NSInteger i = 0;i<8;i++)
 6     {
 7         UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
 8         btn.backgroundColor = [UIColor redColor];
 9         btn.frame = CGRectMake(50+(i%2)*100, 64+(i/2)*100, 90, 90);
10         btn.tag = i;
11         btn.titleLabel.font = [UIFont boldSystemFontOfSize:20];
12         [btn setTitle:[NSString stringWithFormat:@"%d",1+i] forState:UIControlStateNormal];
13         [self.view addSubview:btn];
14         UILongPressGestureRecognizer *longGesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(buttonLongPressed:)];
15         [btn addGestureRecognizer:longGesture];
16         [self.itemArray addObject:btn];
17 
18     }
19 }

 

　　下面，咱們就要思考，如何實現長按移動了，控件的移動而且從新排序，主要是考慮移動的那個控件移動到新的位置，直接看下列代碼，

 1 - (void)buttonLongPressed:(UILongPressGestureRecognizer *)sender
 2 {
 3 
 4     UIButton *btn = (UIButton *)sender.view;
 5     if (sender.state == UIGestureRecognizerStateBegan)
 6     {
 7         startPoint = [sender locationInView:sender.view];
 8         originPoint = btn.center;
 9         [UIView animateWithDuration:Duration animations:^{
10             btn.transform = CGAffineTransformMakeScale(1.1, 1.1);
11             btn.alpha = 0.7;
12         }];
13        
14     }
15     else if (sender.state == UIGestureRecognizerStateChanged)
16     {
17         
18         CGPoint newPoint = [sender locationInView:sender.view];
19         CGFloat deltaX = newPoint.x-startPoint.x;
20         CGFloat deltaY = newPoint.y-startPoint.y;
21         btn.center = CGPointMake(btn.center.x+deltaX,btn.center.y+deltaY);
22         //NSLog(@"center = %@",NSStringFromCGPoint(btn.center));
23         NSInteger index = [self indexOfPoint:btn.center withButton:btn];
24         if (index<0)
25         {
26             contain = NO;
27         }
28         else
29         {
30             [UIView animateWithDuration:Duration animations:^{
31                 
32                 CGPoint temp = CGPointZero;
33                 UIButton *button = _itemArray[index];
34                 temp = button.center;
35                 button.center = originPoint;
36                 btn.center = temp;
37                 originPoint = btn.center;
38                 contain = YES;
39 
40             }];
41         } 
44     }
45     else if (sender.state == UIGestureRecognizerStateEnded)
46     {
47         [UIView animateWithDuration:Duration animations:^{
48             
49            btn.transform = CGAffineTransformIdentity;
50            btn.alpha = 1.0;
51             if (!contain)
52             {
53                  btn.center = originPoint;
54             }
55         }];
56     }
57 }

　　下面這個方法用來判斷要移動的button將要移動到的位置的center是否是在button數組（itemArray）元素的位置中，若是是，返回i 新位置原來的button是數組中得第幾個元素，不然，返回-1。

 1 - (NSInteger)indexOfPoint:(CGPoint)point withButton:(UIButton *)btn
 2 {
 3     for (NSInteger i = 0;i<_itemArray.count;i++)
 4     {
 5         UIButton *button = _itemArray[i];
 6         if (button != btn)
 7         {
 8             if (CGRectContainsPoint(button.frame, point))
 9             {
10                 return i;
11             }
12         }
13     }
14     return -1;
15 }

　　這樣，咱們經過位置判斷，讓控件的位置得以改變。