UIWebView截取长图

#import "ViewController.h"

@interface ViewController ()
@property(strong,nonatomic)UIWebView * webView;
@end

@implementation ViewController




#define IS_RETINA ([[UIScreen mainScreen] respondsToSelector:@selector(displayLinkWithTarget:selector:)] && ([UIScreen mainScreen].scale == 2.0))

- (void)createPDFfromUIView:(UIView*)aView saveToDocumentsWithFileName:(NSString*)aFilename
{
    UIWebView *webView = (UIWebView*)aView;
    
    int height = webView.scrollView.contentSize.height;
    
    CGFloat screenHeight = webView.bounds.size.height;
    
    int pages = ceil(height / screenHeight);
    
    NSMutableData *pdfData = [NSMutableData data];
    UIGraphicsBeginPDFContextToData(pdfData, webView.bounds, nil);
    CGRect frame = [webView frame];
    for (int i = 0; i < pages; i++) {
        // Check to screenHeight if page draws more than the height of the UIWebView
        if ((i+1) * screenHeight  > height) {
            CGRect f = [webView frame];
            f.size.height -= (((i+1) * screenHeight) - height);
            [webView setFrame: f];
        }
        
        UIGraphicsBeginPDFPage();
        CGContextRef currentContext = UIGraphicsGetCurrentContext();
        //      CGContextTranslateCTM(currentContext, 72, 72); // Translate for 1" margins
        
        [[[webView subviews] lastObject] setContentOffset:CGPointMake(0, screenHeight * i) animated:NO];
        [webView.layer renderInContext:currentContext];
    }
    
    UIGraphicsEndPDFContext();
    // Retrieves the document directories from the iOS device
    NSArray* documentDirectories = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES);
    
    NSString* documentDirectory = [documentDirectories objectAtIndex:0];
    NSString* documentDirectoryFilename = [documentDirectory stringByAppendingPathComponent:aFilename];
    
    // instructs the mutable data object to write its context to a file on disk
    [pdfData writeToFile:documentDirectoryFilename atomically:YES];
    [webView setFrame:frame];
}

- (UIImage*)webviewToImage:(UIWebView*)webView
{
    int currentWebViewHeight = webView.scrollView.contentSize.height;
    int scrollByY = webView.frame.size.height;
    
    [webView.scrollView setContentOffset:CGPointMake(0, 0)];
    
    NSMutableArray* images = [[NSMutableArray alloc] init];
    
    CGRect screenRect = webView.frame;
    
    int pages = currentWebViewHeight/scrollByY;
    if (currentWebViewHeight%scrollByY > 0) {
        pages ++;
    }
    
    for (int i = 0; i< pages; i++)
    {
        if (i == pages-1) {
            if (pages>1)
                screenRect.size.height = currentWebViewHeight - scrollByY;
        }
        
        if (IS_RETINA)
            UIGraphicsBeginImageContextWithOptions(screenRect.size, NO, 0.0f);
        else
            UIGraphicsBeginImageContext( screenRect.size );
        if ([webView.layer respondsToSelector:@selector(setContentsScale:)]) {
            webView.layer.contentsScale = [[UIScreen mainScreen] scale];
        }
        //UIGraphicsBeginImageContext(screenRect.size);
        CGContextRef ctx = UIGraphicsGetCurrentContext();
        [[UIColor blackColor] set];
        CGContextFillRect(ctx, screenRect);
        
        [webView.layer renderInContext:ctx];
        
        UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        
        if (i == 0)
        {
            scrollByY = webView.frame.size.height;
        }
        else
        {
            scrollByY += webView.frame.size.height;
        }
        [webView.scrollView setContentOffset:CGPointMake(0, scrollByY)];
        [images addObject:newImage];
    }
    
    [webView.scrollView setContentOffset:CGPointMake(0, 0)];
    
    UIImage *resultImage;
    
    if(images.count > 1) {
        //join all images together..
        CGSize size;
        for(int i=0;i<images.count;i++) {
            
            size.width = MAX(size.width, ((UIImage*)[images objectAtIndex:i]).size.width );
            size.height += ((UIImage*)[images objectAtIndex:i]).size.height;
        }
        
        if (IS_RETINA)
            UIGraphicsBeginImageContextWithOptions(size, NO, 0.0f);
        else
            UIGraphicsBeginImageContext(size);
        if ([webView.layer respondsToSelector:@selector(setContentsScale:)]) {
            webView.layer.contentsScale = [[UIScreen mainScreen] scale];
        }
        CGContextRef ctx = UIGraphicsGetCurrentContext();
        [[UIColor blackColor] set];
        CGContextFillRect(ctx, screenRect);
        
        int y=0;
        for(int i=0;i< images.count;i++) {
            
            UIImage* img = [images objectAtIndex:i];
            [img drawAtPoint:CGPointMake(0,y)];
            y += img.size.height;
        }
        
        resultImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
    } else {
        
        resultImage = [images objectAtIndex:0];
    }
    [images removeAllObjects];
    return resultImage;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    _webView = [[UIWebView alloc] initWithFrame:CGRectMake(0, 0,768 , 1004)];
    NSURLRequest * request = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:@"http://www.qq.com"]];
    [_webView loadRequest:request];
    [_webView setScalesPageToFit:YES];
    [self.view addSubview:_webView];
    
    UIButton * btn = [[UIButton alloc] initWithFrame:CGRectMake(10, 10, 200, 50)];
    [btn addTarget:self action:@selector(btnPressed:) forControlEvents:UIControlEventTouchUpInside];
    [btn setTitle:@"Snapshot" forState:UIControlStateNormal];
    [btn setBackgroundColor:[UIColor redColor]];
    [self.view addSubview:btn];
}

- (void)btnPressed:(id)sender
{
    NSLog(@"%@",NSStringFromCGSize(_webView.scrollView.contentSize));
    UIImage * image = [self webviewToImage:_webView];
    NSLog(@"__________________%@",NSStringFromCGSize(image.size));
    UIImageWriteToSavedPhotosAlbum(image,nil,NULL,NULL);
    
    NSDateFormatter *formatter =[[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"yyyyMMddHHmmss"];
    NSString *currentTime = [formatter stringFromDate:[NSDate date]];
    NSString * filename = [NSString stringWithFormat:@"%@.pdf",currentTime];
    [self createPDFfromUIView:_webView saveToDocumentsWithFileName:filename];
    
}

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


@end