Error handling in Swift helps you deal with unexpected issues like network problems, bad input, or file read errors without crashing your app. Swift gives you a clean way to manage these situations using do-try-catch, so you can throw errors when something goes wrong and catch them in one place to handle them properly.<\/p>\n\n\n\n
enum FileError: Error {\n case fileNotFound\n case unreadable\n case encodingFailed\n}<\/code><\/pre>\n\n\n\nThrow an Error in a Function<\/h3>\n\n\n\nfunc readFile(name: String) throws -> String {\n guard name == \"data.txt\" else {\n throw FileError.fileNotFound\n }\n return \"File content\"\n}<\/code><\/pre>\n\n\n\nHandle the Error with do-try-catch<\/h3>\n\n\n\ndo {\n let content = try readFile(name: \"wrong.txt\")\n print(content)\n} catch FileError.fileNotFound {\n print(\"\u26a0\ufe0f File not found.\")\n} catch {\n print(\"\u26a0\ufe0f An unknown error occurred: \\(error)\")\n}<\/code><\/pre>\n\n\n\nChoosing the Right try Approach in Swift<\/h2>\n\n\n\nSyntax<\/strong><\/td>Description<\/strong><\/td><\/tr>try<\/strong><\/td>Use inside do-catch to handle errors<\/td><\/tr> try?<\/strong><\/td>Converts the result to an optional, returns nil if error occurs<\/td><\/tr> try!<\/strong><\/td>Force try \u2014 crashes if an error is thrown (only use when you’re sure it won’t fail)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\nlet result = try? readFile(name: \"data.txt\") \/\/ Optional(\"File content\")
let force = try! readFile(name: \"data.txt\") \/\/ Unsafe if error is thrown<\/pre>\n\n\n\nCustom Error Messages<\/h3>\n\n\n\n
You can conform your error enum to LocalizedError or CustomStringConvertible to provide better messages:<\/p>\n\n\n\n
extension FileError: LocalizedError {\n var errorDescription: String? {\n switch self {\n case .fileNotFound: return \"The file could not be found.\"\n case .unreadable: return \"The file is unreadable.\"\n case .encodingFailed: return \"The file could not be encoded.\"\n }\n }\n}<\/code><\/pre>\n\n\n\nConclusion<\/h2>\n\n\n\n