iOS中正确的截屏姿势（代码）

来自 http://blog.0xbbc.com/2014/12/ios%E4%B8%AD%E6%AD%A3%E7%A1%AE%E7%9A%84%E6%88%AA%E5%B1%8F%E5%A7%BF%E5%8A%BF/

昨天写了个用到截屏功能的插件，结果问题不断，今天终于解决好了，把debug过程中所有尝试过的截屏方法都贴出来吧～

• 第一种

这是iOS 3时代开始就被使用的方法，它被废止于iOS 7。iOS的私有方法，效率很高。

#import <QuartzCore/QuartzCore.h>
extern "C" CGImageRef UIGetScreenImage();
UIImage * screenshot(void) NS_DEPRECATED_IOS(3_0,7_0);
UIImage * screenshot(){
    UIImage *image = [UIImage imageWithCGImage:UIGetScreenImage()];
    return image;
}

• 第二种

这是在比较常见的截图方法，不过不支持Retina屏幕。

UIImage * screenshot(UIView *);
UIImage * screenshot(UIView *view){
    UIGraphicsBeginImageContext(view.frame.size);
    [view.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

• 第三种

从iPhone 4、iPod Touch 4开始，Apple逐渐采用Retina屏幕，于是在iOS 4的SDK中我们有了，上面的截图方法也自然变成了这样。

UIImage * screenshot(UIView *) NS_AVAILABLE_IOS(4_0);
UIImage * screenshot(UIView *view){
    if(UIGraphicsBeginImageContextWithOptions != NULL)
    {
        UIGraphicsBeginImageContextWithOptions(view.frame.size, NO, 0.0);
    } else {
        UIGraphicsBeginImageContext(view.frame.size);
    }
    [view.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

• 第四种

或许你会说有时Hook的是一个按钮的方法，用第三个方法的话，根本找不到view来传值，不过还好，iOS 7又提供了一些UIScreen的API。

UIImage * screenshot(void) NS_AVAILABLE_IOS(7_0);

UIImage * screenshot(){
    UIView * view = [[UIScreen mainScreen] snapshotViewAfterScreenUpdates:YES];
    if(UIGraphicsBeginImageContextWithOptions != NULL)
    {
        UIGraphicsBeginImageContextWithOptions(view.frame.size, NO, 0.0);
    } else {
        UIGraphicsBeginImageContext(view.frame.size);
    }
    [view.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

• 第五种

@interface SBScreenShotter : NSObject
+ (id)sharedInstance;
- (void)saveScreenshot:(_Bool)arg1;
@end

然后直接

[[SBScreenShotter sharedInstance] saveScreenshot:YES];

一道白光之后，咱们就模拟了用户截屏的动作，不过这个方法在只需要截屏时比较好，如果要对屏幕录像（其实就是不断截图）的话，那不得闪瞎了。。而且我们也拿不到UIImage的实例去拼成一个视频呀。即使通过Hook别的类拿到UIImage的实例，这个私有API的效率大概也是达不到30FPS的视频要求的。

那么现在我们有5种方法了，第一种是私有API，私有API通常效率和质量都比Documented API的好，可是它在iOS 7以后就被废除了啊，就没有别的了吗？

答案当然是————有的！用Private Framework来完成这项任务！直接走底层拿屏幕的缓冲数据，然后生成UIImage的实例。

• 第六种

#import <IOMobileFrameBuffer.h>
#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>
#import <IOKit/IOKit.h>
#import <IOSurface/IOSurface.h>

extern "C" IOReturn IOSurfaceLock(IOSurfaceRef buffer, uint32_t options,uint32_t *seed);
extern "C" IOReturn IOSurfaceUnlock(IOSurfaceRef buffer, uint32_t options,uint32_t *seed);
extern "C" size_t IOSurfaceGetWidth(IOSurfaceRef buffer);
extern "C" size_t IOSurfaceGetHeight(IOSurfaceRef buffer);
extern "C" IOSurfaceRef IOSurfaceCreate(CFDictionaryRef properties);
extern "C" void *IOSurfaceGetBaseAddress(IOSurfaceRef buffer);
extern "C" size_t IOSurfaceGetBytesPerRow(IOSurfaceRef buffer);

extern const CFStringRef kIOSurfaceAllocSize;
extern const CFStringRef kIOSurfaceWidth;
extern const CFStringRef kIOSurfaceHeight;
extern const CFStringRef kIOSurfaceIsGlobal;
extern const CFStringRef kIOSurfaceBytesPerRow;
extern const CFStringRef kIOSurfaceBytesPerElement;
extern const CFStringRef kIOSurfacePixelFormat;

enum
{
    kIOSurfaceLockReadOnly  =0x00000001,
    kIOSurfaceLockAvoidSync =0x00000002
};

UIImage * screenshot(void);

UIImage * screenshot(){
    IOMobileFramebufferConnection connect;
    kern_return_t result;
CoreSurfaceBufferRef screenSurface = NULL;
    io_service_t framebufferService =IOServiceGetMatchingService(kIOMasterPortDefault,IOServiceMatching("AppleH1CLCD"));
if(!framebufferService)
        framebufferService = IOServiceGetMatchingService(kIOMasterPortDefault,IOServiceMatching("AppleM2CLCD"));
if(!framebufferService)
        framebufferService = IOServiceGetMatchingService(kIOMasterPortDefault,IOServiceMatching("AppleCLCD"));

result = IOMobileFramebufferOpen(framebufferService, mach_task_self(), 0, &connect);
result = IOMobileFramebufferGetLayerDefaultSurface(connect, 0, &screenSurface);

    uint32_t aseed;
    IOSurfaceLock((IOSurfaceRef)screenSurface, 0x00000001, &aseed);
    size_t width = IOSurfaceGetWidth((IOSurfaceRef)screenSurface);

    size_t height = IOSurfaceGetHeight((IOSurfaceRef)screenSurface);
    CFMutableDictionaryRef dict;
size_t pitch = width*4, size = width*height*4;

    int bPE=4;

    char pixelFormat[4] = {'A','R','G','B'};
    dict = CFDictionaryCreateMutable(kCFAllocatorDefault, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
    CFDictionarySetValue(dict, kIOSurfaceIsGlobal, kCFBooleanTrue);
    CFDictionarySetValue(dict, kIOSurfaceBytesPerRow,CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &pitch));
    CFDictionarySetValue(dict, kIOSurfaceBytesPerElement,CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &bPE));
    CFDictionarySetValue(dict, kIOSurfaceWidth,CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &width));
    CFDictionarySetValue(dict, kIOSurfaceHeight,CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &height));
    CFDictionarySetValue(dict, kIOSurfacePixelFormat,CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, pixelFormat));
    CFDictionarySetValue(dict, kIOSurfaceAllocSize,CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &size));

    IOSurfaceRef destSurf = IOSurfaceCreate(dict);
    IOSurfaceAcceleratorRef outAcc;
    IOSurfaceAcceleratorCreate(NULL, 0, &outAcc);

    IOSurfaceAcceleratorTransferSurface(outAcc, (IOSurfaceRef)screenSurface, destSurf, dict, NULL);
    IOSurfaceUnlock((IOSurfaceRef)screenSurface, kIOSurfaceLockReadOnly, &aseed);
CFRelease(outAcc);

    CGDataProviderRef provider =  CGDataProviderCreateWithData(NULL,  IOSurfaceGetBaseAddress(destSurf), (width * height * 4), NULL);

    CGImageRef cgImage = CGImageCreate(width, height, 8,
8*4, IOSurfaceGetBytesPerRow(destSurf),
 CGColorSpaceCreateDeviceRGB(), kCGImageAlphaNoneSkipFirst|kCGBitmapByteOrder32Little, provider, NULL, YES, kCGRenderingIntentDefault);

    UIImage *image = [UIImage imageWithCGImage:cgImage];
    return image;
}

需要注意的是，第五种方法需要修改一下IOMobileFramebuffer的头文件。

typedef void * IOMobileFramebufferConnection;

In the reversed header, IOMobileFramebufferConnection is typedef'd toio_connect_t, which is typedef'd to io_object_t, which is mach_port_t, which is__darwin_mach_port_t, which is __darwin_mach_port_name_t, which is__darwin_natural_t, which is unsigned int! Int just happens to be pointer-sized on 32-bit, but is not under 64-bit。

——StackoverFlow

修改好的头文件顺便也丢上来吧，解压后放在Project的根目录下。

如果你使用的是theos的话，记得在Makefile里写上，

YOUR_TWEAK_NAME_PRIVATE_FRAMEWORKS = IOSurface IOKit IOMobileFramebuffer

YOUR_TWEAK_NAME_CFLAGS = -I./headers/ -I./headers/IOSurface

如果是XCode上的Logos Tweak的话，在Build Settings -> Search Paths -> Header Search Paths里面添加一项：$(PROJECT_DIR)/YOUR_PROJECT_NAME/headers, 搜索方式为recursive. 最后在Build Phases里Link上IOSurface IOKit IOMobileFramebuffer这三个私有Framework。