ImageIO实战

ImageIO框架基于C语言读写UIImage，同时也支持颜色管理和访问图像元数据。

下面为大家展示获取照片缩略图的源代码代码。

////  YJUtilsImageIO.swift//  YJImageIO////  CSDN:http://blog.csdn.net/y550918116j//  GitHub:https://github.com/937447974/Blog////  Created by yangjun on 16/1/14.//  Copyright © 2016年 阳君. All rights reserved.//import UIKitimport ImageIO/// ImageIO库工具类public struct YJUtilsImageIO {    // MARK: -     /// 获取UIImage的缩略图    static func createThumbnailImageFromImage(image: UIImage) -> UIImage? {        guard let data = UIImagePNGRepresentation(image) else {            return nil        }        guard let cgImage = YJUtilsImageIO.createThumbnailImageFromData(data, imageSize: data.length) else {            return nil        }        return UIImage(CGImage: cgImage)    }    /// 获取UIImage的缩略图    static func createThumbnailImageFromData(data: NSData, var imageSize: Int) -> CGImageRef? {        // Create an image source from NSData; no options.        // Make sure the image source exists before continuing.        guard let imageSource = CGImageSourceCreateWithData(data as CFDataRef, nil) else {            print("Image source is NULL.")            return nil        }        // Package the integer as a  CFNumber object. Using CFTypes allows you to more easily create the options dictionary later.        let thumbnailSize: CFNumberRef = CFNumberCreate(kCFAllocatorDefault, CFNumberType.IntType, &imageSize)        // Set up the thumbnail options.        let keys: [CFStringRef] = [kCGImageSourceCreateThumbnailWithTransform, kCGImageSourceCreateThumbnailFromImageIfAbsent, kCGImageSourceThumbnailMaxPixelSize]        let values:[CFTypeRef] = [kCFBooleanTrue, kCFBooleanTrue , thumbnailSize]        var kcBacks = kCFTypeDictionaryKeyCallBacks        var vcBacks = kCFTypeDictionaryValueCallBacks        let options: CFDictionaryRef = CFDictionaryCreate(kCFAllocatorDefault, UnsafeMutablePointer(UnsafePointer<Void>(keys)), UnsafeMutablePointer(UnsafePointer<Void>(values)), 2, &kcBacks, &vcBacks)        // Create the thumbnail image using the specified options.        let thumbnailImage = CGImageSourceCreateThumbnailAtIndex(imageSource, 0, options)        // Release the options dictionary and the image source, when you no longer need them.        /* swift 废弃        CFRelease(thumbnailSize)        CFRelease(options)        CFRelease(imageSource)        */        // Make sure the thumbnail image exists before continuing.        guard thumbnailImage != nil else {            print("Thumbnail image not created from image source.")            return nil        }        return thumbnailImage    }}

你还可以使用swift的高级封装实现，可参考如下方法。

// return image as PNG. May return nil if image has no CGImageRef or invalid bitmap formatpublic func UIImagePNGRepresentation(image: UIImage) -> NSData? // return image as JPEG. May return nil if image has no CGImageRef or invalid bitmap format. compression is 0(most)..1(least)public func UIImageJPEGRepresentation(image: UIImage, _ compressionQuality: CGFloat) -> NSData? 

 

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Appendix

Sample Code

Swift

Related Documentation

Image I/O Programming Guide

Revision History

时间 描述 2016-01-13 博文完成

Copyright

CSDN：http://blog.csdn.net/y550918116j

GitHub：https://github.com/937447974/Blog