再谈iOS GestureRecognizer

现在iPhone5的尺寸已经是4英寸了 不排除接下来会出现4.5 5.0英寸的iPhone,但是众所周知iOS的返回键大多在左上角，随着屏幕尺寸的增大，要按到座上角的返回键就没那么容易啊，所以现在的应用大多都会采用手势，用手势来代替一些按键操作。

所以在这里就回忆一下几种常用的手势咯，碰巧在网上看到一篇好文章，所以就跟着写了个demo 分享给大家

//
//  ViewController.h
//  gestureDemo
//
//  Created by kay_sprint on 13-4-5.
//  Copyright (c) 2013年 cn.edu.scnu. All rights reserved.
//

#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>

@interface ViewController : UIViewController <UIGestureRecognizerDelegate>

@property (weak, nonatomic) IBOutlet UIImageView *imgView;
@end

//
//  ViewController.m
//  gestureDemo
//
//  Created by kay_sprint on 13-4-5.
//  Copyright (c) 2013年 cn.edu.scnu. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()
@property (nonatomic) CGFloat lastScale;
@property (nonatomic) CGFloat lastRotate;
@property (nonatomic) CGFloat firstX;
@property (nonatomic) CGFloat firstY;
@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view, typically from a nib.

    self.imgView.userInteractionEnabled = YES;

    UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)];
    panGestureRecognizer.delegate = self;
    [self.imgView addGestureRecognizer:panGestureRecognizer];

    _lastScale = 1.0;
    UIPinchGestureRecognizer *pinchGestureRecognicer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(handlePinch:)];
    pinchGestureRecognicer.delegate = self;
    [self.imgView addGestureRecognizer:pinchGestureRecognicer];

    _lastRotate = 0.0;
    UIRotationGestureRecognizer *rotateGestureRecognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(handleRotate:)];
    rotateGestureRecognizer.delegate = self;
    [self.imgView addGestureRecognizer:rotateGestureRecognizer];

    UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTap:)];
    tapGestureRecognizer.delegate = self;
    [self.imgView addGestureRecognizer:tapGestureRecognizer];
}

- (void)handlePan:(UIPanGestureRecognizer *)recognizer
{
    CGPoint translatedPoint = [recognizer translationInView:self.view];

    if(recognizer.state == UIGestureRecognizerStateBegan) {

        _firstX = [[recognizer view] center].x;
        _firstY = [[recognizer view] center].y;
    }

    translatedPoint = CGPointMake(translatedPoint.x + _firstX, translatedPoint.y + _firstY);
    [recognizer.view setCenter:translatedPoint];

    if(recognizer.state == UIGestureRecognizerStateEnded) {
        CGFloat finalX = translatedPoint.x + (.2 * [recognizer velocityInView:self.view].x);
        CGFloat finalY = translatedPoint.y + (.2 * [recognizer velocityInView:self.view].y);

        if(UIDeviceOrientationIsPortrait([[UIDevice currentDevice] orientation])) {

            if(finalX < 0) {
                finalX = 0;
            } else if(finalX > 768) {
                finalX = 768;
            }

            if(finalY < 0) {
                finalY = 0;
            } else if(finalY > 1024) {
                finalY = 1024;
            }
        } else {

            if(finalX < 0) {
                finalX = 0;
            } else if(finalX > 1024) {
                finalX = 1024;
            }

            if(finalY < 0){
                finalY = 0;
            } else if(finalY > 768) {
                finalY = 768;
            }
        }

        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDuration:.5];
        [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
        [recognizer.view setCenter:CGPointMake(finalX, finalY)];
        [UIView commitAnimations];
    }
}

- (void)handlePinch:(UIPinchGestureRecognizer *)recognizer
{
    if(recognizer.state == UIGestureRecognizerStateEnded) {
        _lastScale = 1.0;
        return;
    }

    
    CGFloat scale = 1.0 - (_lastScale - recognizer.scale); //计算两次的差值

    CGAffineTransform currentTransform = recognizer.view.transform;
    CGAffineTransform newTransform = CGAffineTransformScale(currentTransform, scale, scale);
    [recognizer.view setTransform:newTransform];

    _lastScale = recognizer.scale;
}

- (void)handleRotate:(UIRotationGestureRecognizer *)recognizer
{
    if(recognizer.state == UIGestureRecognizerStateEnded) {
        _lastRotate = 0.0;
        return;
    }

    CGFloat rotate = 0.0 - (_lastRotate - recognizer.rotation);
    CGAffineTransform currentTransform = recognizer.view.transform;
    CGAffineTransform newTransform = CGAffineTransformRotate(currentTransform, rotate);
    [recognizer.view setTransform:newTransform];

    _lastRotate = recognizer.rotation;
}

- (void)handleTap:(UITapGestureRecognizer *)recognizer
{
    //cancel all the animation
    [recognizer.view.layer removeAllAnimations];
}

//delegate
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return ![gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]; //pan不能和其他手势一起触发
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

代码比较简单，这里就不多说了