ios 在Objective-C中将所有文本转换为小写
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Converting all text to lower case in Objective-C
提问by inFever
I have a textfield in my iOS app where the user is supposed to input some text. But I was wondering if there is any way to convert the users input to lowercase letters.
我的 iOS 应用程序中有一个文本字段，用户应该在其中输入一些文本。但我想知道是否有任何方法可以将用户输入转换为小写字母。
I remember in C# it was something like Convert.ToLowerbut I can't seem to figure out how to do it in Objective-C.
我记得在 C# 中它有点像，Convert.ToLower但我似乎无法弄清楚如何在 Objective-C 中做到这一点。
回答by David R?nnqvist
There is a method called lowercaseStringon NSString. NSStringcontains plenty of methods for string manipulation, please read the documentation.
有一个叫方法lowercaseString上NSString。NSString包含大量的字符串操作方法，请阅读文档。
NSString *myString = @"Hello, World!";
NSString *lower = [myString lowercaseString]; // this will be "hello, world!"
回答by Josh O'Connor
Swift 3:
斯威夫特 3：
let upperCasedString = "UPPERCASED"
let lowerCasedString = upperCasedString.lowercased()
//prints "uppercased"
回答by Tamás Sengel
If you want to use a specific Localewhen converting a string to lowercase, use lowercaseStringWithLocale(lowercased(with: Locale)in Swift 3+).
如果您想Locale在将字符串转换为小写时使用特定字符，请使用lowercaseStringWithLocale(lowercased(with: Locale)在 Swift 3+ 中)。
Objective-C
目标-C
NSString *myString = @"Hello, World!";
NSLocale *locale = [NSLocale localeWithLocaleIdentifier:@"en_US"];
NSString *lower = [myString lowercaseStringWithLocale:locale];
Swift 3+
斯威夫特 3+
let myString = "Hello, World!"
let locale = Locale(identifier: "en_US")
let lower = myString.lowercased(with: locale)
