I don't know what to tell you. When you build and run something under Qt Creator, you are running in a different environment than on the actual device (or in a test bed or on your desktop). Paths are different, the "current directory" is different, and so forth. "QAbstractSeries" is probably defined in a QML file associated with the Qt Charts package, and either you aren't deploying that file on iOS or you aren't deploying it in a search path that QML is using on iOS.

On my 5.4.1 distribution, "QAbstractSeries" is defined in the qabstractseries.h file down in the Charts source tree, and is referenced as a Component in the plugins.qmltypes file in the chartsqml2 directory.

Have you followed the instructions on Deploying QML Applications?