本節(jié)知識(shí)點(diǎn)
- 字符
- 字符串
- 字符串常用方法
- 遍歷字符串中的所有字符
- 計(jì)算字符串長(zhǎng)度
- 字符串拼接
- 格式化字符串
- 字符串比較
- 判斷前后綴
- 大小寫(xiě)轉(zhuǎn)換
- 轉(zhuǎn)換為基本數(shù)據(jù)類(lèi)型
- 字符串和數(shù)組轉(zhuǎn)換
- 字符串包含索引
- 字符串替換
- 字符串的截取
1. 字符
- 對(duì)比 OC 與 Swift 中字符的區(qū)別
char charValue = 'a';//OC當(dāng)中的字符:
var charValue1:Character = "a" //swift當(dāng)中的字符:
-
Swift和OC字符不一樣
- 1.Swift是用雙引號(hào)
- 2.Swift中的字符類(lèi)型和OC中的也不一樣
- OC中的字符占一個(gè)字節(jié),因?yàn)樗话珹SCII表中的字符
- Swift中的字符除了可以存儲(chǔ)ASCII表中的字符還可以存儲(chǔ)unicode字符.
- OC的字符是遵守ASCII標(biāo)準(zhǔn)的,
- Swift的字符是遵守unicode標(biāo)準(zhǔn), 所以可以存放世界上所有國(guó)家語(yǔ)言的字符(大部分)
char charValue = '豪'; //OC當(dāng)中:錯(cuò)誤
var charValue2:Character = "豪" //swift當(dāng)中: 正確
-
注意: 雙引號(hào)中只能放一個(gè)字符, 如下是錯(cuò)誤寫(xiě)法
var charValue3:Character = "ab" // 直接報(bào)錯(cuò)
2. 字符串
C OC Swift三種語(yǔ)法的對(duì)比較
//C:
char *stringValue = "ab";
char stringArr = "ab";
//OC:
NSString *stringValue = "ab";
//Swift
var stringValue1 = "ab"
- C語(yǔ)言中的字符串是以\0結(jié)尾的, 例如:
char *stringValue = "abc\0bcd";
printf("%s", stringValue);
//輸出結(jié)果: abc
- OC語(yǔ)言中的字符串也是以\0結(jié)尾的, 例如:
NSString *stringValue = @"abc\0bcd";
NSLog(@"%@", stringValue);
- swift當(dāng)中的字符串和C語(yǔ)言/OC語(yǔ)言中的字符串是不一樣的, 不是一
\0結(jié)束
var stringValue = "abc\0bcd"
print(stringValue)
//輸入結(jié)果: abcbcd
3. 字符串常用方法
3.1 遍歷字符串中的所有字符
let str = "CD豪"
// 遍歷字符串中所有的字符
for c in str.characters{
print(c)
}
// 輸出結(jié)果:
//C
//D
//豪
3.2 計(jì)算字符串長(zhǎng)度
//C:
char *stringValue = "CD豪";
printf("%tu", strlen(stringValue));
//輸出結(jié)果:5
//OC:
NSString *stringValue = @"CD豪";
NSLog(@"%tu", stringValue.length);
//輸出結(jié)果:3 以UTF16計(jì)算
let str = "CD豪"
// 獲取字符串的長(zhǎng)度
let length = str.characters.count // 計(jì)算字符個(gè)數(shù)
let blen = str.lengthOfBytesUsingEncoding(NSUTF8StringEncoding)// 計(jì)算字符串的字節(jié)數(shù)
print(length) // 3
print(blen) // 5
3.3 字符串拼接
//C:
char str1[] = "abc";
char *str2 = "bcd";
char *str = strcat(str1, str2);
printf("%s",str);
//輸出結(jié)果: abcbcd
//OC:
NSMutableString *str1 = [NSMutableString stringWithString:@"abc"];
NSString *str2 = @"bcd";
[str1 appendString:str2];
NSLog(@"%@", str1);
//輸出結(jié)果: abcbcd
//swift:
var str1 = "chen";
var str2 = "dehao";
var str = str1 + str2;
print(str)
//輸出結(jié)果:chendehao
3.4 格式化字符串
//OC:
NSString *str =
[NSMutableString
stringWithFormat:@"http://blog.csdn.net/chendehao001/pic/%tu.png", @10];
NSLog(@"%@", str);
//輸入結(jié)果: http://blog.csdn.net/chendehao001/pic/10.png
//swift:
var index = 10
var str3 = "http://blog.csdn.net/chendehao001/pic/\(index).png"
print(str3)
//輸入結(jié)果: http://blog.csdn.net/chendehao001/pic/10.png
// 拼接過(guò)程格式化
let min = 1
let second = 3
// 注意 format: ,arguments: 這個(gè)方法中的 aguments 不要敲錯(cuò), 沒(méi)有提示, 如果寫(xiě)錯(cuò)就不會(huì)現(xiàn)相應(yīng)輸出, 也不會(huì)報(bào)錯(cuò)哦
let timeStr = String(format: "%02d:%02d", arguments: [min,second])
print(timeStr) // 輸出結(jié)果
3.5 字符串比較
//oc:
NSString *str1 = @"abc";
NSString *str2 = @"abc";
if ([str1 compare:str2] == NSOrderedSame){
NSLog(@"相等");
}else{
NSLog(@"不相等");
}
//輸出結(jié)果:相等
// oc
NSString *str1 = @"abc";
NSString *str2 = @"abc";
if ([str1 isEqualToString:str2]){
NSLog(@"相等");
}else{
NSLog(@"不相等");
}
//輸出結(jié)果:相等
//Swift:(== / != / >= / <=), 和C語(yǔ)言的strcmp一樣是逐個(gè)比較
var str4 = "abc";
var str5 = "abc";
if str4 == str5{
print("相等");
}else{
print("不相等");
}
//輸出結(jié)果:相等
var str6 = "abd";
var str7 = "abc";
if str6 >= str7{
print("大于等于");
}else{
print("不大于等于");
}
//輸出結(jié)果: 大于等于
3.6 判斷前后綴
//OC:
NSString *str = @"http://blog.csdn.net/chendehao001";
if ([str hasPrefix:@"http"]) {
NSLog(@"是url");
}
if ([str hasSuffix:@"chendehao001"]) {
NSLog(@"是頂級(jí)域名");
}
//輸出結(jié)果:
//是url
//是頂級(jí)域名
//Swift:
var str8 = "http://blog.csdn.net/chendehao001"
if str8.hasPrefix("http") {
print("是url");
}
if str8.hasSuffix("chendehao001") {
print("是頂級(jí)域名");
}
//輸出結(jié)果:
//是url
//是頂級(jí)域名
3.7 大小寫(xiě)轉(zhuǎn)換
//OC:
NSString *str = @"abc.txt";
NSLog(@"%@", [str uppercaseString]);
NSLog(@"%@", [str lowercaseString]);
//輸出結(jié)果: ABC.TXT
//abc.txt
// 轉(zhuǎn)換大小寫(xiě)
var str8 = "chendehao.TEXT"
print(str8.uppercaseString) // 輸出結(jié)果 CHENDEHAO.TEXT
print(str8.lowercaseString) // 輸出結(jié)果 chendehao.text
var str1 = "Chen"
var str2 = "dehao"
print(str1.capitalizedString) // 輸出結(jié)果 : Chen
print(str2.capitalizedString) // 輸出結(jié)果 : Dehao
3.8 轉(zhuǎn)換為基本數(shù)據(jù)類(lèi)型
//OC:
NSString *str = @"250";
NSInteger number = [str integerValue];
NSLog(@"%tu", number);
//輸出結(jié)果: 250
// swift
//如果str不能轉(zhuǎn)換為整數(shù), 那么可選類(lèi)型返回nil
var str10 = "250"
//str10 = "250sb" 不能轉(zhuǎn)換所以可能為nil
var number:Int? = Int(str10)
if number != nil{
//以前的版本println會(huì)自動(dòng)拆包, 現(xiàn)在的不會(huì)
print(number!)
}
var str9 = "250"
var number1: Int? = Int(str9) // Optional(250)
var number1fromStr = (str9 as NSString).integerValue // 250
var number2: Int = Int(str9)! //250
var number3 = Int(str9) //Optional(250)
var str10 = "250sb"
var number4:Int? = Int(str10) // nil
var number5 = Int(str10) // nil
var str11 = "100"
var sr1 = (str11 as NSString).integerValue //Swift 2.0 //=100
var a = (str11 as NSString).intValue //=100
var l = (str11 as NSString).longLongValue //=100
var str12 = "10.8"
var f = (str12 as NSString).floatValue //=10.8
var d = (str12 as NSString).doubleValue //=10.8
var str13 = "true"
var b = (str13 as NSString).boolValue //=true // BOOL 類(lèi)型
3.9 字符串和數(shù)組轉(zhuǎn)換
var str1WillTransform = "boy, girl, man, woman"
let strTransformArray = str1WillTransform.componentsSeparatedByString(",")
print(strTransformArray) // ["boy", " girl", " man", " woman"]
var str2WillTransform = "boy,girl,man 10 20 30"
let charset = NSCharacterSet(charactersInString:", ") // 注意: 雙引號(hào)里有逗號(hào)和空格
let str2Array = str2WillTransform.componentsSeparatedByCharactersInSet(charset)
print(str2Array) //["boy", "girl", "man", "10", "20", "30"]
3.10 字符串包含索引
//字符串包含
var str2 = "dehao"
var str5 = "chendehao"
let rangeOfString = str5.rangeOfString(str2)
print(rangeOfString!)// 結(jié)果: 4..<9
let startIndex = rangeOfString?.startIndex
print(startIndex!) // 結(jié)果: 4
3.11 字符串替換 replace
var strReplace = "My name is Aarak"
// swift3.0 將移除的的寫(xiě)法
let subRange = Range(start: strReplace.startIndex,end: strReplace.startIndex.advancedBy(2))
strReplace.replaceRange(subRange, with: "Your")
print(strReplace) // Your name is Aarak
// 推薦寫(xiě)法
let subRange1 = Range(strReplace.startIndex ..< strReplace.startIndex.advancedBy(4))
strReplace.replaceRange( subRange1, with: "CDH")
print(strReplace) // CDH name is Aarak
// 區(qū)分大小寫(xiě)搜索與替換
var str2Replace = strReplace.stringByReplacingOccurrencesOfString("Aarak", withString: "CD豪")
print(str2Replace) // CDH name is Aarak --> CDH name is CD豪
// 不分大小寫(xiě)搜索與替換
str2Replace = strReplace.stringByReplacingOccurrencesOfString("aaraK", withString: "DeHAO陳",options: NSStringCompareOptions.CaseInsensitiveSearch,range: nil)
print(str2Replace) // CDH name is Aarak --> CDH name is DeHAO陳
3.12 字符串的截取
- 轉(zhuǎn)化為 OC 的語(yǔ)法做字符串截取
// 截取字符, 方式一:
let urlString = "http://blog.csdn.net/chendehao001"
let header = (urlString as NSString).substringToIndex(4) // http
let footer = (urlString as NSString).substringFromIndex(21) // chendehao001
let range = NSMakeRange(21, 9) //
let middle = (urlString as NSString).substringWithRange(range) // chendehao
print(middle) //chendehao
// 截取字符, 方式二:
let endIndex = urlString.startIndex.advancedBy(21)
let starIndex = urlString.endIndex.advancedBy(-3)
let header1 = urlString.substringToIndex(endIndex)
let footer1 = urlString.substringFromIndex(starIndex)
// Range(start: ,end: ) 這個(gè)寫(xiě)法在 Swift3.0 移除
let range1 = Range(start: endIndex.advancedBy(0),end: starIndex.advancedBy(-0))
let middle1 = urlString.substringWithRange(range1)
print(middle1) // chendehao
let range2 = Range( urlString.startIndex.advancedBy(21) ..< urlString.endIndex.advancedBy(-3))
let middle2 = urlString.substringWithRange(range2)
print(middle2) // chendehao
