字符串处理(正则表达式、NSScanner扫描、CoreParse解析器)－b

转载

mb5fe32930661bd 2016-04-21 23:25:00

搜索

在一个字符串中搜索子字符串

最灵活的方法

1	`- (NSRange)rangeOfString:(NSString )aString options:(NSStringCompareOptions)mask range:(NSRange)searchRange locale:(NSLocale )locale`

格式化字符串

3个方法

1 2 3	`-initWithFormat:` `-initWithFormat:arguments:` `+stringWithFormat:`

整数

可以同时工作在32位和64位的

1 2 3	`uint64_t p = 2305843009213693951;` `NSString *s = [NSString stringWithFormat:@``"The ninth Mersenne prime is %llu"``, (unsigned long long) p];` `// "The ninth Mersenne prime is 2305843009213693951"`

Modifier	d, i	o, u, x, X
hh	signed char	unsigned char
h	short	unsigned short
(none)	int	unsigned int
l(ell)	long	unsigned long
j	intmax_t	uintmax_t
t	ptrdiff_t
z		size_t

转换规则

1 2 3 4 5	`int m = -150004021;` `uint n = 150004021U;` `NSString *s = [NSString stringWithFormat:@``"d:%d i:%i o:%o u:%u x:%x X:%X"``, m, m, n, n, n, n];` `// "d:-150004021 i:-150004021 o:1074160465 u:150004021 x:8f0e135 X:8F0E135"` `//o是八进制`

设置最小字段宽度和最小数字位数

1 2 3 4 5 6	`int m = 42;` `NSString s = [NSString stringWithFormat:@``"'%4d' '%-4d' '%+4d' '%4.3d' '%04d'"``, m, m, m, m, m];` `// "[ 42] [42 ] [ +42] [ 042] [0042]"` `m = -42;` `NSString s = [NSString stringWithFormat:@``"'%4d' '%-4d' '%+4d' '%4.3d' '%04d'"``, m, m, m, m, m];` `// "[ -42] [-42 ] [ -42] [-042] [-042]"`

%p可打印指针，和%#x不同的是它可以同时在32位和64位执行

浮点数

使用%f和%g

1 2 3 4 5	`double v[5] = {12345, 12, 0.12, 0.12345678901234, 0.0000012345678901234};` `NSString s = [NSString stringWithFormat:@``"%g %g %g %g %g"``, v[0], v[1], v[2], v[3], v[4]];` `// "12345 12 0.12 0.123457 1.23457e-06"` `NSString s = [NSString stringWithFormat:@``"%f %f %f %f %f"``, v[0], v[1], v[2], v[3], v[4]];` `// "12345.000000 12.000000 0.120000 0.123457 0.000001"`

多行文字

使用来

1 2 3 4 5 6 7 8 9 10	`NSString *limerick = @``"A lively young damsel named Menzies` `"` `@``"Inquired: «Do you know what this thenzies?»` `"` `@``"Her aunt, with a gasp,` `"` `@``"Replied: "``It``'s a wasp,` `"` `@"And you'``re holding the end where the stenzies.` `";`

等价写法

1 2 3 4 5 6	`NSString *limerick = @``"A lively young damsel named Menzies` `Inquired: «Do you know what this thenzies?»` `Her aunt, with a gasp,` `Replied: "``It``'s a wasp,` `And you'``re holding the end where the stenzies.` `";`

更简洁的方法

1	`NSString * string = @``"The man "` `@``"who knows everything "` `@``"learns nothing"` `@``"."``;`

替换字符串

NSMutableString的四个方法

1 2 3 4	`-deleteCharactersInRange:` `-insertString:atIndex:` `-replaceCharactersInRange:withString:` `-replaceOccurrencesOfString:withString:options:range:`

NSString的方法

1 2 3	`-stringByReplacingOccurrencesOfString:withString:` `-stringByReplacingOccurrencesOfString:withString:options:range:` `-stringByReplacingCharactersInRange:withString:`

NSMutableString不会创建新字符串，性能会好点

1 2 3 4 5 6 7	`NSMutableString string;` `// 假设我们已经有了一个名为 string 的字符串` `// 现在要去掉它的一个前缀，做法如下:` `NSString prefix = @``"WeDon’tWantThisPrefix"` `NSRange r = [string rangeOfString:prefix options:NSAnchoredSearch range:NSMakeRange(0, string.length) locale:nil];` `if` `(r.location != NSNotFound) {` `[string deleteCharactersInRange:r];` `}`

连接字符串

1 2	`NSArray names = @[``"Hildr"``, @``"Heidrun"``, @``"Gerd"``, @``"Guðrún"``, @``"Freya"``, @``"Nanna"``, @``"Siv"``, @``"Skaði"``, @``"Gróa"``];` `NSString result = [names componentsJoinedByString:@``", "``];`

字符串解析

正则表达式

1 2 3 4 5 6 7 8 9 10	`NSError error = nil;` `NSString pattern = @``"(\w+) = #(\p{Hex_Digit}{6})"``;` `NSRegularExpression expression = [NSRegularExpression regularExpressionWithPattern:pattern` `options:0` `error:&error];` `NSTextCheckingResult result = [expression firstMatchInString:string` `options:0` `range:NSMakeRange(0, string.length)];` `NSString key = [string substringWithRange:[result rangeAtIndex:1]];` `NSString value = [string substringWithRange:[result rangeAtIndex:2]];`

将字符串分解成数组，使用componentsSeparatedByString:这个方法，或者 enumerateSubstringsInRange:options:usingBlock:。如果是按照行来进行分解可以使用option这个参数传NSStringEnumerationByLines

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19	`NSString input = @“` `backgroundColor =` `#ff0000` `textColor =` `#0000ff` `"` `NSString pattern = @"``(\w+) =` `#([\da-f]{6})";` `NSRegularExpression expression = [NSRegularExpression regularExpressionWithPattern:pattern` `options:0` `error:NULL];` `NSArray lines = [input componentsSeparatedByCharactersInSet:[NSCharacterSet newlineCharacterSet]];` `NSMutableDictionary result = [NSMutableDictionary dictionary];` `for` `(NSString line` `in` `lines) {` `NSTextCheckingResult textCheckingResult = [expression firstMatchInString:line` `options:0` `range:NSMakeRange(0, line.length)];` `NSString key = [line substringWithRange:[textCheckingResult rangeAtIndex:1]];` `NSString* value = [line substringWithRange:[textCheckingResult rangeAtIndex:2]];` `result[key] = value;` `}` `return` `result;`

扫描

NSScanner

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22	`NSScanner scanner = [NSScanner scannerWithString:string];` `//默认情况下，扫描器会跳过所有空格符和换行符。但这里我们只希望跳过空格符` `scanner.charactersToBeSkipped = [NSCharacterSet whitespaceCharacterSet];` `//定义一个十六进制字符集` `NSCharacterSet hexadecimalCharacterSet =` `[NSCharacterSet characterSetWithCharactersInString:@``"0123456789abcdefABCDEF"``];` `NSMutableDictionary result = [NSMutableDictionary dictionary];` `while` `(!scanner.isAtEnd) {` `NSString key = nil;` `NSString value = nil;` `NSCharacterSet letters = [NSCharacterSet letterCharacterSet];` `BOOL didScan = [scanner scanCharactersFromSet:letters intoString:&key] &&` `[scanner scanString:@``"="` `intoString:NULL] &&` `[scanner scanString:@``"#"` `intoString:NULL] &&` `[scanner scanCharactersFromSet:hexadecimalCharacterSet intoString:&value] &&` `value.length == 6;` `result[key] = value;` `[scanner scanCharactersFromSet:[NSCharacterSet newlineCharacterSet]` `intoString:NULL];` `// 继续扫描下一行` `}` `return` `result;`

解析器

设计一个能够用(100,0,255)或者#ff0000这样的字符来定义颜色的方法。

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60	`- (NSDictionary )parse:(NSString )string error:(NSError *)error` `{` `self.scanner = [NSScanner scannerWithString:string];` `self.scanner.charactersToBeSkipped = [NSCharacterSet whitespaceCharacterSet];` `NSMutableDictionary result = [NSMutableDictionary dictionary];` `NSCharacterSet letters = [NSCharacterSet letterCharacterSet]` `while` `(!self.scanner.isAtEnd) {` `NSString key = nil;` `UIColor value = nil;` `BOOL didScan = [self.scanner scanCharactersFromSet:letters intoString:&key] &&` `[self.scanner scanString:@``"="` `intoString:NULL] &&` `[self scanColor:&value];` `result[key] = value;` `[self.scanner scanCharactersFromSet:[NSCharacterSet newlineCharacterSet]` `intoString:NULL];` `// 继续扫描下一行` `}` `}` `- (BOOL)scanColor:(UIColor )out` `{` `return` `[self scanHexColorIntoColor:out] \|\| [self scanTupleColorIntoColor:out];` `}` `//扫描设置#ff0000这样的` `- (BOOL)scanHexColorIntoColor:(UIColor )out` `{` `NSCharacterSet hexadecimalCharacterSet =` `[NSCharacterSet characterSetWithCharactersInString:@``"0123456789abcdefABCDEF"``];` `NSString colorString = NULL;` `if` `([self.scanner scanString:@``"#"` `intoString:NULL] &&` `[self.scanner scanCharactersFromSet:hexadecimalCharacterSet` `intoString:&colorString] &&` `colorString.length == 6) {` `out = [UIColor colorWithHexString:colorString];` `return` `YES;` `}` `return` `NO;` `}` `- (BOOL)scanTupleColorIntoColor:(UIColor *)out` `{` `NSInteger red, green, blue = 0;` `BOOL didScan = [self.scanner scanString:@``"("` `intoString:NULL] &&` `[self.scanner scanInteger:&red] &&` `[self.scanner scanString:@``","` `intoString:NULL] &&` `[self.scanner scanInteger:&green] &&` `[self.scanner scanString:@``","` `intoString:NULL] &&` `[self.scanner scanInteger:&blue] &&` `[self.scanner scanString:@``")"` `intoString:NULL];` `if` `(didScan) {` `out = [UIColor colorWithRed:(CGFloat)red/255.` `green:(CGFloat)green/255.` `blue:(CGFloat)blue/255.` `alpha:1];` `return` `YES;` `}` `else` `{` `return` `NO;` `}` `}`

符号化处理

先进星扫描，使用NSScanner来解析这个表达式

1 2	`myView.left = otherView.right * 2 + 10` `viewController.view.centerX + myConstant <= self.view.centerX`

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35	`NSScanner scanner = [NSScanner scannerWithString:contents];` `NSMutableArray tokens = [NSMutableArray array];` `while` `(![scanner isAtEnd]) {` `for` `(NSString operator` `in` `@[@``"="``, @``"+"``, @``""``, @``">="``, @``"<="``, @``"."``]) {` `if` `([scanner scanString:operator intoString:NULL]) {` `[tokens addObject:operator];` `}` `}` `}` `//接下来识别非符号的只包含字母的string` `NSString result = nil;` `if` `([scanner scanCharactersFromSet:[NSCharacterSet letterCharacterSet]` `intoString:&result]) {` `[tokens addObject:result];` `}` `//NSScanner有scanDouble:来扫描double` `double doubleResult = 0;` `if` `([scanner scanDouble:&doubleResult]) {` `[tokens addObject:@(doubleResult)];` `}` `//完成后用将需要解析的表达式放入试试` `NSString example = @``"myConstant = 100` `"` `@``"` `myView.left = otherView.right * 2 + 10` `"` `@``"viewController.view.centerX + myConstant <= self.view.centerX"``;` `NSArray result = [self.scanner tokenize:example];` `NSArray expected = @[@``"myConstant"``, @``"="``, @100, @``"myView"``, @``"."``, @``"left"``,` `@``"="``, @``"otherView"``, @``"."``, @``"right"``, @``"*"``, @2, @``"+"``,` `@10, @``"viewController"``, @``"."``, @``"view"``, @``"."``,` `@``"centerX"``, @``"+"``, @``"myConstant"``, @``"<="``, @``"self"``,` `@``"."``, @``"view"``, @``"."``, @``"centerX"``];` `XCTAssertEqualObjects(result, expected);`

进行语法解析，需要语法分析库描述我们的语言。下面代码就是为那个布局约束语言写的解析语法，用的扩展的巴科斯：

1 2 3 4 5 6 7 8	`constraint = expression comparator expression` `comparator =` `"="` `\|` `">="` `\|` `"<="` `expression = keyPath` `"."` `attribute addMultiplier addConstant` `keyPath = identifier \| identifier` `"."` `keyPath` `attribute =` `"left"` `\|` `"right"` `\|` `"top"` `\|` `"bottom"` `\|` `"leading"` `\|` `"trailing"` `\|` `"width"` `\|` `"height"` `\|` `"centerX"` `\|` `"centerY"` `\|` `"baseline"` `addMultiplier =` `"*"` `atom` `addConstant =` `"+"` `atom` `atom = number \| identifier`

还有很多Objective-C的语法解析，更多的可以在CocoaPods上找到：

1 2 3 4 5 6 7 8 9 10 11 12 13 14	`NSString* grammarString = [@[` `@``"Atom ::= num@'Number' \| ident@'Identifier';"``,` `@``"Constant ::= name@'Identifier' '=' value@<Atom>;"``,` `@``"Relation ::= '=' \| '>=' \| '<=';"``,` `@``"Attribute ::= 'left' \| 'right' \| 'top' \| 'bottom' \| 'leading' \| 'trailing' \| 'width' \| 'height' \| 'centerX' \| 'centerY' \| 'baseline';"``,` `@``"Multiplier ::= '*' num@'Number';"``,` `@``"AddConstant ::= '+' num@'Number';"``,` `@``"KeypathAndAttribute ::= 'Identifier' '.' <AttributeOrRest>;"``,` `@``"AttributeOrRest ::= att@<Attribute> \| 'Identifier' '.' <AttributeOrRest>;"``,` `@``"Expression ::= <KeypathAndAttribute> <Multiplier>? <AddConstant>?;"``,` `@``"LayoutConstraint ::= lhs@<Expression> rel@<Relation> rhs@<Expression>;"``,` `@``"Rule ::= <Atom> \| <LayoutConstraint>;"``,` `] componentsJoinedByString:@``"` `"``];`

一个规则匹配后解析器就找到同样名称的类

1 2 3 4 5 6 7	`- (id)parser:(CPParser )parser didProduceSyntaxTree:(CPSyntaxTree )syntaxTree` `NSString *ruleName = syntaxTree.rule.name;` `if` `([ruleName isEqualToString:@``"Attribute"``]) {` `return` `self.layoutAttributes[[[syntaxTree childAtIndex:0] keyword]];` `}` `...` `}`

：

1	`viewController.view.centerX + 20 <= self.view.centerX * 0.5`

可以得到如下结果，方便转换成NSLayoutConstraint对象

1 2 3 4 5 6 7 8 9	`(<Expression: self.keyPath=(viewController, view),` `self.attribute=9,` `self.multiplier=1,` `self.constant=20>` `-1` `<Expression: self.keyPath=(self, view),` `self.attribute=9,` `self.multiplier=0.5,` `self.constant=0>)`

字符串的渲染

UILabel

label默认显示一行，如果设置numberOfLines为大于1的话可以显示指定行数，如果设置为0，则多少行都显示
attributedText属性可以显示富文本
label的font,textColor,textAlignment,shadowColor和shadowOffset属性可以改变外观。
改变程序内所有Label的风格，可以使用[UILabel appearance]方法

UITextField

text field只限于单行
UITextfield实现了UITextInputTraits协议，这个协议需要指定键盘外观和操作等细节。比如显示什么键盘和返回按键响应等
可以通过设置左右辅助视图，或者设置背景来自定义输入框风格了。

UITextView

TableView中显示动态文本

Table view的Delegate有个方法用来计算高度：tableView:heightForRowAtIndexPath:。自定义一个UITableViewCell的子类

1 2 3 4 5 6 7	`- (void)layoutSubviews` `{` `[``super` `layoutSubviews];` `self.textLabel.frame = CGRectInset(self.bounds,` `MyTableViewCellInset,` `MyTableViewCellInset);` `}`

计算真实高度需要使用boundingRectWithSize:options:context: 这个方法

1 2 3 4 5 6 7 8 9 10 11 12	`- (CGFloat)tableView:(UITableView )tableView heightForRowAtIndexPath:(NSIndexPath )indexPath` `{` `CGFloat labelWidth = self.tableView.bounds.size.width - MyTableViewCellInset2;` `NSAttributedString text = [self attributedBodyTextAtIndexPath:indexPath];` `NSStringDrawingOptions options = NSStringDrawingUsesLineFragmentOrigin \|` `NSStringDrawingUsesFontLeading;` `CGRect boundingRect = [text boundingRectWithSize:CGSizeMake(labelWidth, CGFLOAT_MAX)` `options:options` `context:nil];` `return` `(CGFloat) (ceil(boundingRect.size.height) + MyTableViewCellInset*2);` `}`

使用Text Kit和NSAttributedString进行布局

先设置attributes

1 2 3 4 5 6 7 8 9 10 11 12	`CGFloat const fontSize = 15;` `NSMutableDictionary body1stAttributes = [NSMutableDictionary dictionary];` `body1stAttributes[NSFontAttributeName] = [UIFont fontWithName:@``"BodoniSvtyTwoITCTT-Book"` `size:fontSize];` `NSMutableParagraphStyle body1stParagraph = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];` `body1stParagraph.alignment = NSTextAlignmentJustified;` `body1stParagraph.minimumLineHeight = fontSize + 3;` `body1stParagraph.maximumLineHeight = body1stParagraph.minimumLineHeight;` `body1stParagraph.hyphenationFactor = 0.97;` `body1stAttributes[NSParagraphStyleAttributeName] = body1stParag` `raph;`

这里字体为BodoniSvtyTwoITCTT，如果需要查看更多字体可以使用 +[UIFont familyNames]这个方法。为了得到字体的名字，可以使用 +[UIFont fontNamesForFamilyName:]。接下来创建段落的属性

1 2 3 4 5	`NSMutableDictionary bodyAttributes = [body1stAttributes mutableCopy];` `NSMutableParagraphStyle bodyParagraph =` `[bodyAttributes[NSParagraphStyleAttributeName] mutableCopy];` `bodyParagraph.firstLineHeadIndent = fontSize;` `bodyAttributes[NSParagraphStyleAttributeName] = bodyParagraph;`

装饰段落风格，使用装饰字体将文本居中对齐，装饰字符的前后加上空白段落

1 2 3 4 5 6 7 8	`NSMutableDictionary ornamentAttributes = [NSMutableDictionary dictionary];` `ornamentAttributes[NSFontAttributeName] = [UIFont fontWithName:@``"BodoniOrnamentsITCTT"` `size:36];` `NSMutableParagraphStyle ornamentParagraph = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];` `ornamentParagraph.alignment = NSTextAlignmentCenter;` `ornamentParagraph.paragraphSpacingBefore = fontSize;` `ornamentParagraph.paragraphSpacing = fontSize;` `ornamentAttributes[NSParagraphStyleAttributeName] = ornamentParagraph;`

显示数字表格table，表格布局示例

1 2 3 4 5 6 7 8 9 10 11 12	`NSCharacterSet decimalTerminator = [NSCharacterSet` `characterSetWithCharactersInString:decimalFormatter.decimalSeparator];` `NSTextTab decimalTab = [[NSTextTab alloc]` `initWithTextAlignment:NSTextAlignmentCenter` `location:100` `options:@{NSTabColumnTerminatorsAttributeName:decimalTerminator}];` `NSTextTab percentTab = [[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentRight` `location:200` `options:nil];` `NSMutableParagraphStyle tableParagraphStyle =` `[[NSParagraphStyle defaultParagraphStyle] mutableCopy];` `tableParagraphStyle.tabStops = @[decimalTab, percentTab];`

显示列表的属性设置如下

1 2 3 4 5 6 7 8 9 10	`NSMutableDictionary listAttributes = [bodyAttributes mutableCopy];` `NSMutableParagraphStyle listParagraph =` `[listAttributes[NSParagraphStyleAttributeName] mutableCopy];` `listParagraph.headIndent = fontSize * 3;` `listParagraph.firstLineHeadIndent = fontSize;` `NSTextTab listTab = [[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentNatural` `location:fontSize 3` `options:nil];` `listParagraph.tabStops = @[listTab];` `listAttributes[NSParagraphStyleAttributeName] = listParagraph;`