iOS PDF使用CATiledLayer展示

最新推荐文章于 2021-09-06 16:36:53 发布

iChenfy

最新推荐文章于 2021-09-06 16:36:53 发布

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分类专栏： UI 控件相关 iOS 常用相关功能文章标签： ios pdf 文档

本文链接：https://blog.youkuaiyun.com/u012198553/article/details/75255035

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本文介绍了一种使用CATiledLayer逐步加载和显示PDF文档的方法。通过创建自定义的PDFView类并重写其初始化方法，可以高效地将PDF页面渲染到iOS应用中。这种方法能够有效地减少内存占用并提升加载速度。

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采用CATiledLayer分步展示pdf文档

//
//  PDFView.m
//  CFd
//
//  Created by Chenfy on 2017/7/17.
//  Copyright © 2017年 Chenfy. All rights reserved.
//

#import "PDFView.h"

@interface PDFView()
@property(nonatomic,assign)CGPDFPageRef page;

@end

@implementation PDFView

+ (Class)layerClass {
    return [CATiledLayer class];
}

-(instancetype)initWithFrame:(CGRect)frame path:(NSString *)path completion:(void (^)(CGSize))completion
{
    self = [super initWithFrame:frame];
    if (self) {
        NSURL *docURL = [NSURL fileURLWithPath:path];
        CGPDFDocumentRef pdf = CGPDFDocumentCreateWithURL((CFURLRef)docURL);
        CGPDFPageRef page = CGPDFDocumentGetPage(pdf, 2);
        self.page = page;
        CGRect pageRect = CGPDFPageGetBoxRect(page, kCGPDFCropBox);
        CATiledLayer * layer = (CATiledLayer *)self.layer;
        layer.levelsOfDetailBias = 5;

        layer.bounds = pageRect;
        int w = pageRect.size.width;
        int h = pageRect.size.height;

        int levels = 1;
        while (w > 1 && h > 1) {
            levels++;
            w = w >> 1;
            h = h >> 1;
        }
        layer.levelsOfDetail = levels;
        [self setFrame:pageRect];
        if (completion) {
            completion(pageRect.size);
        }
    }
    return self;
}

- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx {
    CGContextDrawPDFPage(ctx, self.page);
}
/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
    // Drawing code
}
*/

@end