Zxing Barcodes Scanner (horse symbol) not compatible with ios / iphone 5s?

[iphone 5s user]

I used the barcode scanner of Zxing group for Android (triangle symbol with red bar in the middle) before - it was perfect.

The one for iphone (horse symbol) does not function. There is no bar and not the typical noise - nothing happens after opening the app despite placing the barcode inside the rectangle.

Does somebody knows why?