iOS如何实现长按拖动控件

　　实现控件拖动的方法有多种，可以使用UICollectionView的代理方法直接实现，但是有些开发者在初始时没有使用UICollectionView创建九宫格，后来增加需求，却要增加这种拖动移动的效果，又不想更改页面的初始控件，那么应该怎么实现呢？

　　方法很简单，首先在@interface创建以下全局变量；

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

　　如图所示，在viewDidLoad里创建了如下的控件布局；

 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，我们就要思考，如何实现长按移动了，控件的移动并且重新排序，主要是考虑移动的那个控件移动到新的位置，直接看下列代码，

- (void)buttonLongPressed:(UILongPressGestureRecognizer *)sender{    UIButton *btn = (UIButton *)sender.view;    if (sender.state == UIGestureRecognizerStateBegan)    {        startPoint = [sender locationInView:sender.view];        originPoint = btn.center;        [UIView animateWithDuration:Duration animations:^{                        btn.transform = CGAffineTransformMakeScale(1.1, 1.1);            btn.alpha = 0.7;        }];           }    else if (sender.state == UIGestureRecognizerStateChanged)    {                CGPoint newPoint = [sender locationInView:sender.view];        CGFloat deltaX = newPoint.x-startPoint.x;        CGFloat deltaY = newPoint.y-startPoint.y;        btn.center = CGPointMake(btn.center.x+deltaX,btn.center.y+deltaY);        //NSLog(@"center = %@",NSStringFromCGPoint(btn.center));        NSInteger index = [self indexOfPoint:btn.center withButton:btn];        if (index<0)        {            contain = NO;        }        else        {            [UIView animateWithDuration:Duration animations:^{                                CGPoint temp = CGPointZero;                UIButton *button = _itemArray[index];                temp = button.center;                button.center = originPoint;                btn.center = temp;                originPoint = btn.center;                contain = YES;            }];        }                    }    else if (sender.state == UIGestureRecognizerStateEnded)    {        [UIView animateWithDuration:Duration animations:^{                       btn.transform = CGAffineTransformIdentity;           btn.alpha = 1.0;            if (!contain)            {                 btn.center = originPoint;            }        }];    }}- (NSInteger)indexOfPoint:(CGPoint)point withButton:(UIButton *)btn{    for (NSInteger i = 0;i<_itemArray.count;i++)    {        UIButton *button = _itemArray[i];        if (button != btn)        {            if (CGRectContainsPoint(button.frame, point))            {                return i;            }        }    }    return -1;}

 

这样，我们通过位置判断的方式，让控件得以重新排列。