NSCharacterSet 中的 NSArray [英] NSArray from NSCharacterSet

问题描述

目前我可以制作如下所示的字母数组

Currently I am able to make array of Alphabets like below

[[NSArray alloc]initWithObjects:@"A",@"B",@"C",@"D",@"E",@"F",@"G",@"H",@"I",@"J",@"K",@"L",@"M",@"N",@"O",@"P",@"Q",@"R",@"S",@"T",@"U",@"V",@"W",@"X",@"Y",@"Z",nil];

知道可以通过

[NSCharacterSet uppercaseLetterCharacterSet]

如何用它做一个数组?

推荐答案

以下代码创建一个包含给定字符集的所有字符的数组.它也适用于基本多语言平面"之外的字符(字符 > U+FFFF，例如 U+10400 DESERET CAPITAL LETTER LONG I).

The following code creates an array containing all characters of a given character set. It works also for characters outside of the "basic multilingual plane" (characters > U+FFFF, e.g. U+10400 DESERET CAPITAL LETTER LONG I).

NSCharacterSet *charset = [NSCharacterSet uppercaseLetterCharacterSet];
NSMutableArray *array = [NSMutableArray array];
for (int plane = 0; plane <= 16; plane++) {
    if ([charset hasMemberInPlane:plane]) {
        UTF32Char c;
        for (c = plane << 16; c < (plane+1) << 16; c++) {
            if ([charset longCharacterIsMember:c]) {
                UTF32Char c1 = OSSwapHostToLittleInt32(c); // To make it byte-order safe
                NSString *s = [[NSString alloc] initWithBytes:&c1 length:4 encoding:NSUTF32LittleEndianStringEncoding];
                [array addObject:s];
            }
        }
    }
}

对于 uppercaseLetterCharacterSet，这给出了一个包含 1467 个元素的数组.但请注意，字符 > U+FFFF 在 NSString 中存储为 UTF-16 代理对，因此例如 U+10400 实际上存储在 NSString 中为 2 个字符 "uD801uDC00".

For the uppercaseLetterCharacterSet this gives an array of 1467 elements. But note that characters > U+FFFF are stored as UTF-16 surrogate pair in NSString, so for example U+10400 actually is stored in NSString as 2 characters "uD801uDC00".

Swift 2 代码可在此问题的其他答案中找到.这是一个 Swift 3 版本，写成扩展方法:

Swift 2 code can be found in other answers to this question. Here is a Swift 3 version, written as an extension method:

extension CharacterSet {
    func allCharacters() -> [Character] {
        var result: [Character] = []
        for plane: UInt8 in 0...16 where self.hasMember(inPlane: plane) {
            for unicode in UInt32(plane) << 16 ..< UInt32(plane + 1) << 16 {
                if let uniChar = UnicodeScalar(unicode), self.contains(uniChar) {
                    result.append(Character(uniChar))
                }
            }
        }
        return result
    }
}

例子:

let charset = CharacterSet.uppercaseLetters
let chars = charset.allCharacters()
print(chars.count) // 1521
print(chars) // ["A", "B", "C", ... "]

(请注意，某些字符可能不会出现在用于显示结果.)

(Note that some characters may not be present in the font used to display the result.)

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