rangeOfString

rangeOfString is a method used in Cocoa and Cocoa Touch to locate a substring within an NSString. It returns an NSRange describing the location and length of the first occurrence of the specified string in the receiver. If the substring is not found, the returned range has a location of NSNotFound.

There are several overloads of the method. Common signatures include: - (NSRange)rangeOfString:(NSString *)aString; - (NSRange)rangeOfString:(NSString *)aString options:(NSStringCompareOptions)mask; - (NSRange)rangeOfString:(NSString *)aString options:(NSStringCompareOptions)mask range:(NSRange)searchRange. The aString parameter is the substring to locate. The options parameter (mask) controls aspects of the search, such as case sensitivity, diacritic sensitivity, or search direction. The optional searchRange parameter confines the search to a portion of the receiver.

Return value: An NSRange with the location and length of the found substring. If not found, location equals NSNotFound and length is 0. The range can be used to extract the substring or to determine presence without creating a new string.

Usage considerations: By default the search is case-sensitive and diacritic-sensitive. To perform case-insensitive searches, include NSCaseInsensitiveSearch in the mask; other options can adjust handling of diacritics, equality, and direction. The method is commonly used for validation, parsing, and text processing in Objective-C projects.

Swift and bridge: In Swift, String provides range(of:) returning an optional Range<String.Index>, and NSString’s rangeOfString methods are available via bridging for compatibility with legacy code.