An example of a magnifier in iOS

This article implements the magnifier function. The usage is as follows:

1. Import the MagnifierView class to the project. : Http://pan.baidu.com/s/1eUz2Q

ViewController. h

#import 
 
  #import "MagnifierView.h"@interface ViewController : UIViewController@property (strong , nonatomic) MagnifierView* loop;@property (strong , nonatomic) NSTimer* touchTimer;@end
 

ViewController. m

- (void)viewDidLoad{    [super viewDidLoad];// Do any additional setup after loading the view, typically from a nib.        UIImageView* image = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"changmen.jpg"]];    image.frame  = CGRectMake(0, 0, 320, 548);    [self.view addSubview:image];}- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {        self.touchTimer = [NSTimer scheduledTimerWithTimeInterval:0.5f target:self selector:@selector(addLoop) userInfo:nil repeats:NO];        if (self.loop == nil) {        self.loop = [[MagnifierView alloc] init];        self.loop.viewToMagnify = self.view;    }        UITouch* touch = [touches anyObject];    self.loop.touchPoint = [touch locationInView:self.view];    [self.loop setNeedsDisplay];    }- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {[self handleAction:touches];}- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {[self.touchTimer invalidate];self.touchTimer = nil;    self.loop = nil;}- (void)handleAction:(id)timerObj {NSSet *touches = timerObj;UITouch *touch = [touches anyObject];self.loop.touchPoint = [touch locationInView:self.view];[self.loop setNeedsDisplay];}- (void)addLoop {// add the loop to the superview.  if we add it to the view it magnifies, it'll magnify itself!//[self.superview addSubview:loop];[self.loop makeKeyAndVisible];// here, we could do some nice animation instead of just adding the subview...}