要缩小通过两个触摸点的观点(iOS)

于AppDelegate.m档,创建一个视图控制器

#import "MAYAppDelegate.h"
#import "MAYViewController.h"
@implementation MAYAppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.
    
    MAYViewController *root = [[MAYViewController alloc] init];
    self.window.rootViewController = root;
    [root release];
    
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    return YES;
}

创建一个视图控制器MAYViewController,在视图控制器MAYViewController.m文件里,创建一个视图

#import "MAYViewController.h"
#import "Touch.h"
@interface MAYViewController ()

@end

@implementation MAYViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
      
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    self.view.backgroundColor = [UIColor lightGrayColor];
    Touch *touch = [[Touch alloc] initWithFrame:CGRectMake(50, 150, 200, 200)];
    touch.backgroundColor = [UIColor greenColor];
    [self.view addSubview:touch];
    [touch release];
    
}

新建一个视图类Touch,加入在视图控制器上,在Touch.m文件里实现缩放功能
#import "Touch.h"

@implementation Touch

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
        //设置是否支持多点触摸(YES支持,NO不支持)
        self.multipleTouchEnabled = YES;
    }
    return self;
}
//计算两点之间的距离
- (CGFloat)distance:(CGPoint)point1 point2:(CGPoint)point2
{
    CGFloat dx = point1.x - point2.x;
    CGFloat dy = point1.y - point2.y;
    CGFloat tance = sqrt(pow(dx, 2) + pow(dy, 2));
    return tance;
}


- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    
    if (1 == [touches count]) {
        return;
    }
    //设置触摸点
    NSArray *array = [touches allObjects];
    UITouch *touch1 = [array firstObject];
    UITouch *touch2 = [array lastObject];
    //获取移动前的触摸点
    CGPoint firstPreviousPoint = [touch1 previousLocationInView:self];
    CGPoint secondPreviousPoint = [touch2 previousLocationInView:self];
    
    //获取与移动后的触摸点
    CGPoint firstCurrentPoint = [touch1 locationInView:self];
    CGPoint secondCurrentPoint = [touch2 locationInView:self];
    
    //获取移动前后的两点之间的距离
    CGFloat previousDistance = [self distance:firstPreviousPoint point2:secondPreviousPoint];
    CGFloat currentDistance = [self distance:firstCurrentPoint point2:secondCurrentPoint];
    
    //获取缩放比例
    CGFloat scanl = currentDistance / previousDistance;
    
    //获得缩放后的视图大小
    
    self.bounds = CGRectMake(0, 0, self.bounds.size.width * scanl, self.bounds.size.height * scanl);
    }

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