触摸与手势之拖拽

触摸与手势中要求拖拽出一个半透明黑框，并打印位置和大小

1.源代码

2.效果图

//  ViewController.m

#import "ViewController.h"

#define kScreenWidth [UIScreen mainScreen].bounds.size.width

#define kScreenHeight [UIScreen mainScreen].bounds.size.height

@interface ViewController ()

@end

@implementation ViewController

{

   UIView *_maskView ;//创建一个拖拽视图   

}

- (void)viewDidLoad {

    [superviewDidLoad];

    

   UIImageView *imgView = [[UIImageViewalloc] initWithFrame:CGRectMake(0,0, kScreenWidth,kScreenHeight)];

    imgView.image = [UIImageimageNamed:@"feng.jpeg"];

    [self.viewaddSubview:imgView];

    

    //拖拽手势

    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizeralloc] initWithTarget:selfaction:@selector(panAction:)];

    [self.viewaddGestureRecognizer:pan];

    

    _maskView = [[UIViewalloc] initWithFrame:CGRectZero];

    _maskView.backgroundColor = [UIColorblackColor];

   _maskView.alpha =.5;//设置透明度

    [self.viewaddSubview:_maskView];

    

}

- (void)panAction:(UIPanGestureRecognizer *)pan

{

   static CGPoint firstPoint;

    if (pan.state ==UIGestureRecognizerStateBegan)//开始拖拽

    {

        firstPoint = [panlocationInView:self.view];

       NSLog(@"firstPoint is %@",NSStringFromCGPoint(firstPoint));

    }elseif (pan.state ==UIGestureRecognizerStateChanged)//拖拽手势移动

    {

       CGPoint lastPoint = [pan locationInView:self.view];

        NSLog(@"lastPoint is %@",NSStringFromCGPoint(lastPoint));

       _maskView.frame =CGRectMake(firstPoint.x, firstPoint.y, (lastPoint.x -firstPoint.x) , (lastPoint.y - firstPoint.y));

        NSLog(@"_maskView.frame is %@",NSStringFromCGRect(_maskView.frame));

    }

    elseif (pan.state ==UIGestureRecognizerStateEnded)//停止拖拽

    {

        _maskView.frame =CGRectZero;

    }

@end

效果图见下：

}