Which AI model writes the most bugs in Swift?

As of Nov 14, 2026, Claude Sonnet 5.5 had the highest relative bug rate in Swift code (1.33, 33% more counted bugs than the Swift average), statistically tied with Claude Opus 5.5 and GPT-6 Astra.

Updated Nov 14, 2026

Best AI model for Swift code

As of Nov 14, 2026, GPT-6.1 Sol had the lowest relative bug rate in Swift code (0.05, 95% fewer counted bugs than the Swift average), among 4 ranked models.

Models ranked by relative bug rate in Swift code. Lower values are better.
Rank	Model	Rate
1	GPT-6.1 Sol	0.05
2= (statistically tied)	Claude Opus 5.5	0.85
3= (statistically tied)	GPT-6 Astra	0.90
4= (statistically tied)	Claude Sonnet 5.5	1.33

1.00 = Swift average · lower is better · = statistically tied

Other languages

TypeScript
Python
JavaScript
SQL
Go
Shell
Rust
Ruby
Vue
Terraform
C#
PHP
Svelte
Java
Kotlin
Dart
Elixir

Questions and answers

Which AI model writes the most bugs in Swift?: As of Nov 14, 2026, Claude Sonnet 5.5 had the highest relative bug rate in Swift code (1.33, 33% more counted bugs than the Swift average), statistically tied with Claude Opus 5.5 and GPT-6 Astra.