iOS与H5交互 询问相机、相册权限的问题 |
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问题背景: 某个H5页面中需要打开手机本地相册及照相机,用户选择某几张图片之后上传至服务器上。纯H5完成的话,当打开相机或者相册时,第一次会正常询问权限,但是如果用户点击了不允许之后,询问弹窗不再能弹出,H5处理不了。 当然简单粗暴地方式就是改为纯原生来写,不过我们的页面已用了很久,只是新增了一个上传的功能,所以还是延续当前页面,只不过改为原生和H5交互的方式,即e页面仍是H5页面,打开相册相机的弹窗改为由原生代码处理,最后将用户选择到的图片传给H5,由H5将数据传给服务端。 中间的交互不再赘述,网上到处都是,只是最后将拿到的数据传给H5这一步有一个小小的坑需注意; 第一步,将图片转化成字符串: //当我们拿到图片之后,会将图片image转化成字符串 NSString *imageStr = [self encodeImageToBase64:image]; //将上述合法的字符串传给H5 [self p_toJSPramaWithImageBase64Str:imageStr];此处,压缩转化中,base64EncodedStringWithOptions的options必须传NSDataBase64EncodingEndLineWithCarriageReturn,否则会失败!!! // 将image转成5兆以内的二进制流,然后转化成base64的字符串 // #define ImageMaxLength 1024.0*1024.0*5 //5M - (NSString *)encodeImageToBase64:(UIImage *)image { NSData *imageData = [image compressWithMaxLength:ImageMaxLength]; return [imageData base64EncodedStringWithOptions:NSDataBase64EncodingEndLineWithCarriageReturn]; }压缩图片 //压缩到多少以内 1024.0*1024.0*5 5兆以内 -(NSData *)compressWithMaxLength:(NSUInteger)maxLength { // Compress by quality CGFloat compression = 1; NSData *data = UIImageJPEGRepresentation(self, compression); //NSLog(@"Before compressing quality, image size = %ld KB",data.length/1024); if (data.length < maxLength) return data; CGFloat max = 1; CGFloat min = 0; for (int i = 0; i < 6; ++i) { compression = (max + min) / 2; data = UIImageJPEGRepresentation(self, compression); //NSLog(@"Compression = %.1f", compression); //NSLog(@"In compressing quality loop, image size = %ld KB", data.length / 1024); if (data.length < maxLength * 0.9) { min = compression; } else if (data.length > maxLength) { max = compression; } else { break; } } //NSLog(@"After compressing quality, image size = %ld KB", data.length / 1024); if (data.length < maxLength) return data; UIImage *resultImage = [UIImage imageWithData:data]; // Compress by size NSUInteger lastDataLength = 0; while (data.length > maxLength && data.length != lastDataLength) { lastDataLength = data.length; CGFloat ratio = (CGFloat)maxLength / data.length; //NSLog(@"Ratio = %.1f", ratio); CGSize size = CGSizeMake((NSUInteger)(resultImage.size.width * sqrtf(ratio)), (NSUInteger)(resultImage.size.height * sqrtf(ratio))); // Use NSUInteger to prevent white blank UIGraphicsBeginImageContext(size); [resultImage drawInRect:CGRectMake(0, 0, size.width, size.height)]; resultImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); data = UIImageJPEGRepresentation(resultImage, compression); //NSLog(@"In compressing size loop, image size = %ld KB", data.length / 1024); } //NSLog(@"After compressing size loop, image size = %ld KB", data.length / 1024); return data; }第二步将数据传给H5: iosSelectImageSuc为和h5约定好的方法 此处要点:字符串必须要拼接 data:image/jpg;base64,否则依然会失败!!!! - (void)p_toJSPramaWithImageBase64Str:(NSString *)imageBase64Str { //oc调js,将图片传给H5 NSString *str = [@"data:image/jpg;base64," stringByAppendingString:imageBase64Str]; NSString *jsStr = [NSString stringWithFormat:@"%@('%@')",@"iosSelectImageSuc",str]; [self.webView evaluateJavaScript:jsStr completionHandler:^(id _Nullable result, NSError * _Nullable error) { NSLog(@"%@--%@",result,error); }]; } |
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