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);

    }