The month of April was something of a mixed blessing to iOS developers and publishers, according to mobile marketing outfit Fiksu.

The Fiksu Cost per Loyal User Index (which reflects marketing costs) rose 10 percent, or 14 cents from March's $1.36.

It now costs $1.50 to buy a user who will open your app or games three times of more - Fiksu's definition of a loyal user.

The Fiksu App Store Competitive Index - which measures the average aggregate daily download volume of the top 200 free US iPhone apps - also rose 11 percent in April to 5.61 million, up from March's 5.02 million.Going up

Speaking on the dual move, Fiksu's CEO Micah Adler said that "three key forces" combined to create increases in volume and costs.

"First, the relentless industry investment in mobile by brands large and small kept competition high.



"Second, the industry’s smooth transition from Apple’s UDID to its new Advertising Identifier (IDFA) actually kept traffic stable when it could have caused some disruption.

"And third, the rapid traction of Facebook mobile app install ads, which may have provided developers with a greater pool of efficient inventory and consequently may have buffered the industry against even greater rises in costs."

It can be argued that the end of the UDID and implementation of the IDFA directly led to the marketing cost increase, as this change prompted many valuable app publishers to enter the marketplace.



Fiksu notes that traditionally, these publishers were reluctant to participate in marketing using UDID but are now being reassured by the advertising-friendly IDFA.