A new survey shows that more than half of app developers consider restrictive policies, such as a lengthy and ever-changing app approval process, the number one obstacle to using Apple's App Store.  An even larger percentage considered "anticompetitive" actions very or somewhat common when attempting to launch an app.

The survey, which pooled together answers from 750 developers from around the world, demonstrates a rocky relationship between app creators and the Apple platform -- which is the world's second largest, according to analytics firm App Annie. The study comes on the heels of recent accusations from Spotify's legal team that Apple's iOS store policies were unfairly giving its streaming music platform, Apple Music, a leg up on all other streaming music apps.

Published by the Application Developers Alliance, a nonprofit organization that represents the app industry, the study also asked developers whether they think anticompetitive practices that give some apps and publishers, such as Apple, an advantage in the marketplace have become more of a problem in recent years. Forty-eight percent said yes.

“This was a survey of mobile app publishers — the majority of whom have voiced displeasure with Apple's behaviors, specifically as related to the conditions of their partnership,” said Jake Ward, chief executive officer of the Application Developers Alliance. “I think that speaks volumes about content creators' view of the way Apple treats them.”

Apple did not immediately respond to a request for comment.

Half of those surveyed said that the app approval process, which is often complicated and slow, was the most hindering feature of the App Store's policy.

Ajay Rajani, who runs start-up and idea accelerator Nex.tt and didn't participate in the study, agrees that Apple's approval process tends to be slow and rigorous, especially compared to the iOS store's main competitor, Google Play. He estimates that it can take four to five days for Apple to get back to a developer, even mentioning one instance in his own experience when it took three weeks, and the platform almost always has feedback. Google Play, on the other hand, will approve or provide feedback within several hours, he said.

However, he mentions that the difference can result in an overall quality gap between the two platforms. "The speed and ease of approval is brilliant for those of us who believe in iteration and love doing it, but it definitely contributes to a lack of unifying standards, UX and quality across the Google Play Store," he said. "Apple's slower. But, look, they know stuff we don't about interface design, engagement and app behavior — so it can be objectively helpful."

Antitrust lawyer and blogger Jarod Bona agrees. "There are strong pro-competitive and business justifications for a restrictive approval process among other policies," he said. "The success of Apple’s application platform depends upon convincing customers to use it, and restrictive policies may weed out weaker or flawed apps." He adds that Google Play, with its breezier review process, takes up a larger market share than Apple and that disgruntled app developers can easily use that platform.

Still, many developers surveyed said that they felt that Apple's strict policies were at times designed to benefit the company's own apps.  One respondent blamed an “uneven playing field being featured by Apple” as the reason why what they consider to be quality apps are not approved. Another respondent said that the greatest threat to competition was “Apple not allowing [a competing] app to be accepted.”

One person cited that rules regarding in-app purchase categories or customer analytics are changed "capriciously," and that these rules are poorly communicated to app developers.

"What is allowed one year is not allowed the next, etc. Because of this, company management and developers NEVER have a good idea of how to build an app," said one respondent. "We only find out when it's done — the most expensive way to discover problems."

Controversy about whether Apple's App Store policies are being unfairly used to quash competition is not new. An FTC investigation into the tech giant was launched last year regarding whether the 30 percent fee that Apple takes for any app purchases on its platform is anticompetitive. The argument is that the fee puts Spotify, Tidal, and other streaming music apps at a disadvantage compared to Apple's own Apple Music, which doesn't have to pay the fee.

In a speech on corporate practices delivered by Sen. Elizabeth Warren (D-Mass.) last month, the senator called out Apple along with Google and Amazon [Jeffrey P. Bezos, chief executive of Amazon.com, owns The Washington Post] as engaging in anticompetitive practices. Apple “has placed conditions on its rivals that make it difficult for them to offer competitive streaming services," she said.

Ward said that surveyed developers did mention the burdens of the 30 percent fee, but felt that the most restrictive policies were the store's cumbersome approval process. "Publishers aren't naive. They understand that the platform that enables them to reach consumers is based on a revenue sharing business model," he said.

"What they do not accept is when that platform stands between them and their consumers."