基于ARKit的iOS无限屏实现，还原锤子发布会效果

- (void)session:(ARSession *)session didUpdateFrame:(ARFrame *)frame {
    matrix_float4x4 mat33 = frame.camera.transform;
    simd_float4 pos = mat33.columns[3];
    float x = pos[0];
    float y = pos[1];
    float z = pos[2];
}

// 用于计算三轴数据的变量
@property (nonatomic, assign) float x_pre;
@property (nonatomic, assign) float x_base;
@property (nonatomic, assign) BOOL hasInitX;
@property (nonatomic, assign) BOOL findXBase;

@property (nonatomic, assign) float y_pre;
@property (nonatomic, assign) float y_base;
@property (nonatomic, assign) BOOL hasInitY;
@property (nonatomic, assign) BOOL findYBase;

@property (nonatomic, assign) float z_pre;
@property (nonatomic, assign) float z_base;
@property (nonatomic, assign) BOOL hasInitZ;
@property (nonatomic, assign) BOOL findZBase;

// val: camera某个轴向的实际坐标值
// pre: 上一个camera坐标值
// base: 标定后的原点
// hasInit: 是否完成了某轴向的初始化
// findBase: 是否完成了某轴向的标定
float calculateOffset(float val, float *pre, float *base, BOOL *hasInit, BOOL *findBase) {
    // 判断translate某轴向的值是否非0，非0说明ARKit完成了初始化
    if (!(*hasInit) && val < 0.0000001f) {
        NSLog(@"init");
        return 0;
    } else {
        *hasInit = YES;
    }
    // 判断ARKit某轴向的两次输出是否差值很小，差值很小时说明已经稳定，将当前位置标定为当前轴向的原点
    if (!(*findBase) && fabs(val - *pre) < 0.01f) {
        NSLog(@"value is stable at %f", val);
        *base = val;
        *findBase = YES;
        return 0;
    }
    // 计算实际translate和标定点之间的距离
    float offset = val - *base;
    *pre = val;
    return offset;
}

- (void)session:(ARSession *)session didUpdateFrame:(ARFrame *)frame {
    matrix_float4x4 mat33 = frame.camera.transform;
    simd_float4 pos = mat33.columns[3];
    // ARCamera的translate
    float x = pos[0];
    float y = pos[1];
    float z = pos[2];
    // 计算相对手机当前位置的偏移量
    float offsetX = calculateOffset(x, &_x_pre, &_x_base, &_hasInitX, &_findXBase);
    float offsetY = calculateOffset(y, &_y_pre, &_y_base, &_hasInitY, &_findYBase);
    float offsetZ = calculateOffset(z, &_z_pre, &_z_base, &_hasInitZ, &_findZBase);
    // 输出稳定的三轴偏移(offsetX, offsetY, offsetZ)
}

// scrollView是SpringBoard.app的桌面SBIconScrollView
CGRect rect = (CGRect){0, 0, scrollView.contentSize};
UIGraphicsBeginImageContextWithOptions(rect.size, false, [UIScreen mainScreen].scale);
[scrollView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *desktopImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

// 截取桌面，作为大图的中间部分middleImage
CGRect rect = (CGRect){0, 0, scrollView.contentSize};
UIGraphicsBeginImageContextWithOptions(rect.size, false, [UIScreen mainScreen].scale);
[scrollView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *middleImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// 从资源文件读取相机和地球，USBResource是一个资源获取的辅助类
UIImage *topImage = [USBResource imageNamed:@"camera.png"];
UIImage *bottomImage = [USBResource imageNamed:@"earth.png"];
// 上下视图的垂直间距
CGFloat imageMargin = 320;
// 相机和地球平铺的水平间距
CGFloat marginH = 80;
// 具体位置计算
CGFloat topImageW = 120;
CGFloat topImageH = 89;
CGFloat bottomImageW = 120;
CGFloat bottomImageH = 120;
// 用于渲染完整图片的上下文
CGSize ctxSize = CGSizeMake(middleImage.size.width, middleImage.size.height + topImageH + bottomImageH + imageMargin * 4);
UIGraphicsBeginImageContextWithOptions(ctxSize, NO, [UIScreen mainScreen].scale);
// add top image: camera
CGFloat topImageX = marginH;
CGFloat topImageY = topImageH + imageMargin;
NSInteger count = (ctxSize.width - marginH) / (topImageW + marginH);
for (NSInteger i = 0; i < count; i++) {
    [topImage drawInRect:CGRectMake(topImageX, topImageY, topImageW, topImageH)];
    topImageX += topImageW + marginH;
}
// add middle image: desktop
[middleImage drawInRect:CGRectMake(0, topImageH + imageMargin * 2, middleImage.size.width, middleImage.size.height)];
// add bottom image: earth
CGFloat bottomImageX = marginH;
CGFloat bottomImageY = ctxSize.height - imageMargin - bottomImageH;
count = (ctxSize.width - marginH) / (bottomImageW + marginH);
for (NSInteger i = 0; i < count; i++) {
    [bottomImage drawInRect:CGRectMake(bottomImageX, bottomImageY, bottomImageW, bottomImageH)];
    bottomImageX += bottomImageW + marginH;
}
// 获取到的"假桌面"图片
UIImage *snapshot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

%hook SBIconScrollView

- (void)setPagingEnabled:(BOOL)enabled {
    static const void *key;
    // 利用关联对象实现防止重复调用
    if (objc_getAssociatedObject(self, key) != nil) {
        %orig(enabled);
        return;
    }
    // 在这里完成初始化
    // ...
    objc_setAssociatedObject(self, key, @"", OBJC_ASSOCIATION_RETAIN);
    %orig(enabled);
}

%end

for (UIWindow *window in [UIApplication sharedApplication].windows) {
        if ([window isKindOfClass:NSClassFromString(@"SBHomeScreenWindow")]) {
            // 找到关键的窗口和控制器
            UIWindow *mainWindow = window;
            UIViewController *mainVc = window.rootViewController;
            break;
        }
}

#import "USBResource.h"

#define BundlePath @"/Library/MobileSubstrate/DynamicLibraries/UltimateSpringBoard.bundle"

@implementation USBResource

+ (UIImage *)imageNamed:(NSString *)name {
    return [UIImage imageWithContentsOfFile:[BundlePath stringByAppendingPathComponent:name]];
}

@end

// 添加一个Respring按钮
UIButton *closeBtn = [UIButton new];
// ...省略配置过程
[closeBtn addTarget:self action:@selector(closeBtnClick) forControlEvents:UIControlEventTouchUpInside];
[window addSubview:closeBtn];

// 回调方法
%new
- (void)closeBtnClick {
    exit(0);
}