OC字符串的常用方法

网上写的关于字符串常用方法的博客很多，这里我简单做了下总结！不喜勿喷哦！

一.创建字符串

#import <Foundation/Foundation.h>

//NSString

//创建不可变字符串对象的类

//NSMutableString

//创建可变字符串对象的类

//OC语言完全兼容C语言

//OC字符串与C语言字符串区别

//1.OC字符串是一个字符串对象,字符串常量需要用@""包含

//2.C语言字符串用""包含

//3.C语言的字符串以字符的ASCII码形式存储

//4.OC中的字符串以uicode编码(万国码)形式存储

//UTF-8(多字节编码)

//5.打印OC字符串用%@,打印C语言字符串用%s

int main(int argc,constchar * argv[]) {

@autoreleasepool {

NSString *str1 =@"hello world";//@"hello world"是一个常量字符串对象,存储常量区,不可以被修改

NSLog(@"str1 = %@", str1);

//格式化创建字符串对象

//- (instancetype)initWithFormat:(NSString *)format, ...

NSString *str2 = [[NSString alloc] initWithFormat:@"%s%d%@","hello",123,@"world" ];

NSLog(@"str2 = %@", str2);

//用格式化的类方法创建字符串对象

//+ (instancetype)stringWithFormat:(NSString *)format, ...

NSString *str3 = [NSString stringWithFormat:@"%s%d%@","qiafdn",456,@"ffds"];

NSLog(@"str3 = %@", str3);

//用给定的字符串对象创建字符串对象

NSString *str4=@"中国教育";

NSString *str5 = [[NSString alloc] initWithString:str4];

NSLog(@"str5 = %@", str5);

//用C的字符串创建OC的字符串对象

NSString *str6 = [[NSString alloc] initWithUTF8String:"qifdfdg中国jiaoyu"];

NSLog(@"str6 = %@", str6);

NSString *str7 = [[NSString alloc] initWithCString:"我的qifdfg" encoding:NSUTF8StringEncoding];

NSLog(@"str7 = %@", str7);

//创建一个空的字符串对象 @""

NSString *str8 = [NSString string];

NSLog(@"str8 = %@", str8);

NSString *str9 = [[NSString alloc] init];

NSLog(@"str9 = %@", str9);

//跟initWithString相对应

NSString *str10 = [NSString stringWithString:str7];

NSLog(@"str10 = %@", str10);

//跟initWithUTF8String相对应

NSString *str11 = [NSString stringWithUTF8String:"hello world中国"];

NSLog(@"str11 = %@", str11);

//跟initWithCString相对应

NSString *str12 = [NSString stringWithCString:"zhongguo" encoding:NSUTF8StringEncoding];

NSLog(@"str12 = %@", str12);

}

return0;

}

二.NSString的常用方法

#import <Foundation/Foundation.h>

//NSString

int main(int argc,constchar * argv[]) {

@autoreleasepool {

NSString *str1 =@"hello world中国";

//求字符串长度

NSUInteger len = [str1 length];

NSLog(@"len = %li", len);

//获取字符串指定位置的字符

unichar ch = [str1 characterAtIndex:13];

NSLog(@"ch = %C", ch);//%C打印unichar字符 %c打印ASCII字符

//字符串提取

//从传入下标位置提取子串到字符串结束

NSString *subStr1 = [str1 substringFromIndex:4];

NSLog(@"subStr1 = %@", subStr1);

//提取子串到指定位置(不包含下标位置字符)

NSString *subStr2 = [str1 substringToIndex:7];

NSLog(@"subStr2 = %@",subStr2);

//提取指定范围内的字符串

NSRange range = {6,5};

NSString *subStr3 = [str1 substringWithRange:range];

NSLog(@"subStr3 = %@",  subStr3);

//NSMakeRange();//构建NSRange变量

NSString *subStr4 = [str1 substringWithRange:NSMakeRange(2,6)];

NSLog(@"subStr4 = %@", subStr4);

//字符串比较

NSString *str2 = [NSString stringWithCString:"hallo world中国" encoding:NSUTF8StringEncoding];

NSString *str3 = [NSString stringWithUTF8String:"hello world中国"];

NSComparisonResult result = [str2 compare:str3];

if (result == NSOrderedAscending) {//递增

NSLog(@"str2 < str3");

}

elseif(result == NSOrderedDescending)//递减

{

NSLog(@"str2 > str3");

}

else

{

NSLog(@"str2 == str3");

}

//以大小写不敏感方式比较字符串

//[str2 caseInsensitiveCompare:str3];

//判断两个字符串是否相等

//- (BOOL)isEqualToString:(NSString *)aString;

BOOL ret = [str2 isEqualTo:str3];

if (ret==YES) {

NSLog(@"str2 == str3");

}

else

{

NSLog(@"str2 != str3");

}

//判断前缀子串

//- (BOOL)hasPrefix:(NSString *)aString;

BOOL ret1 = [@"www.baidu.com" hasPrefix:@"www."];

NSLog(@"ret1 = %d", ret1);

//判断后缀子串

//- (BOOL)hasSuffix:(NSString *)aString;

BOOL ret2 = [@"www.hao123.com" hasSuffix:@"com"];

NSLog(@"ret2 = %d", ret2);

//判断是否包含子串(10.10macos)

BOOL ret3 = [@"hao123" containsString:@"hao"];

NSLog(@"ret3 = %d", ret3);

//查找子串

NSString *str4 = [[NSString alloc] initWithFormat:@"%s","hello world qidfafddnworldfedffsng"];

NSRange range1 =[str4 rangeOfString:@"world"];

if (range1.location == NSNotFound) {//不能查找对应的子串,返回long类型最大值

NSLog(@"没有查找到字串 notfound = %lu", NSNotFound);

}

else

{

NSLog(@"location = %lu length = %lu", range1.location, range1.length);

}

//倒序查找子串

NSRange range2 = [str4 rangeOfString:@"world" options:NSBackwardsSearch];

NSLog(@"location = %li length = %li", range2.location, range2.length);

//字符串追加

//并不是直接在原字符串的末尾追加字符串,而是利用传入的字符串及原字符串创建一个新的字符串

NSString *str5 =@"hello";

NSLog(@"%p", str5);

str5 = [str5 stringByAppendingString:@"world"];

NSLog(@"str5 = %@", str5);

NSLog(@"%p", str5);

//格式化追加字符串

NSString *str6 =@"qfdfdng";

str6 = [str6 stringByAppendingFormat:@"%d%s",123,"helloworld"];

NSLog(@"str6 = %@", str6);

//把字符换串对象转换成整型浮点型

int a = [@"12345" intValue];

float f = [@"3.14" floatValue];

NSLog(@"a = %d f = %.2f", a, f);

//返回公共前缀子串

NSString *str7 = [@"www.baidu.com" commonPrefixWithString:@"www.hao123.com"options:NSLiteralSearch];

NSLog(@"str7 = %@", str7);

//大小写转换

//把小写字母转换成大写字母

NSString *str8 = [@"baidu中国" uppercaseString];

NSLog(@"str8 = %@", str8);

//把大写字母转换成小写字母

NSString *str9 = [@"BaiDU" lowercaseString];

NSLog(@"str9 = %@", str9);

//把每个单词的首字母大写

NSString *str10= [@"bai du qian feng" capitalizedString];

NSLog(@"str10 = %@", str10);

//字符串替换

//- (NSString *)stringByReplacingOccurrencesOfString:(NSString *)target withString:(NSString *)replacement

NSString *str11=@"hello world qiafdfnfdg hello world hello hell qdfdfnfdg";

str11 = [str11 stringByReplacingOccurrencesOfString:@"hello" withString:@"welcome"];

NSLog(@"str11 = %@", str11);

//替换指定范围内的字符

//- (NSString *)stringByReplacingCharactersInRange:(NSRange)range withString:(NSString *)replacement

NSString *str12 =@"hello world qianfeng";

str12 = [str12 stringByReplacingCharactersInRange:NSMakeRange(12,8) withString:@"welcome"];

NSLog(@"str12 = %@", str12);

//把OC的字符串对象转换成C字符串

NSLog(@"%s", [@"hello world" UTF8String]);

//用网址的内容生成OC字符串对像

//- (instancetype)initWithContentsOfURL:(NSURL *)url encoding:(NSStringEncoding)enc error:(NSError **)error;

//+ (instancetype)stringWithContentsOfURL:(NSURL *)url encoding:(NSStringEncoding)enc error:(NSError **)error;

NSURL *url= [[NSURL alloc] initWithString:@"http://www.baidu.com"];

NSString *urlContent = [[NSString alloc] initWithContentsOfURL:url encoding:NSUTF8StringEncoding error:nil];//nil空指针

NSLog(@"urlContent = %@", urlContent);

//用文件的内容生成字符串

//- (instancetype)initWithContentsOfFile:(NSString *)path encoding:(NSStringEncoding)enc error:(NSError **)error;

//+ (instancetype)stringWithContentsOfFile:(NSString *)path encoding:(NSStringEncoding)enc error:(NSError **)error;

NSString *fileContent = [NSString stringWithContentsOfFile:@"/Users/zhangxueming/Desktop/json.txt"encoding:NSUTF8StringEncoding error:nil];

NSLog(@"fileContent = %@", fileContent);

}

return0;

}

三.NSSMUtableString的常用方法

#import <Foundation/Foundation.h>

//NSMutableString 继承与NSString

//所有NSString类的方法NSMutableString都可以使用

int main(int argc,constchar * argv[]) {

@autoreleasepool {

//创建指定容量大小的可变字符串对象

//+ (NSMutableString *)stringWithCapacity:(NSUInteger)capacity;

NSMutableString *mulStr1 = [[NSMutableString alloc] initWithCapacity:20];

NSLog(@"mulStr1 = %@", mulStr1);

//替换指定范围内的字符

//- (void)replaceCharactersInRange:(NSRange)range withString:(NSString *)aString;

NSMutableString *mulStr2 = [[NSMutableString alloc] initWithString:@"hello world qianfdfsfefdg"];

[mulStr2 replaceCharactersInRange:NSMakeRange(6,5) withString:@"welcome"];

NSLog(@"mulStr2 = %@", mulStr2);

//在指定位置增加字符串

NSMutableString *mulStr3 = [[NSMutableString alloc] initWithFormat:@"梦想中国"];

[mulStr3 insertString:@"hello world" atIndex:2];

NSLog(@"mulStr3 = %@", mulStr3);

//删除指定范围内的字符

NSMutableString *mulStr4 = [NSMutableString stringWithUTF8String:"热爱hello world中国"];

[mulStr4 deleteCharactersInRange:NSMakeRange(2,11)];

NSLog(@"mulStr4 = %@", mulStr4);

//追加字符串

NSMutableString *mulStr5 = [NSMutableString stringWithString:@"helloworld"];

[mulStr5 appendString:@"qidffdf"];

NSLog(@"mulStr5 = %@", mulStr5);

//格式化追加字符串

NSMutableString *mulStr6 = [NSMutableString stringWithFormat:@"%s%d","hello",12345];

[mulStr6 appendFormat:@"%.2f%@",3.14,@"world"];

NSLog(@"mulStr6 = %@", mulStr6);

//修改字符串

NSMutableString *mulStr7 = [[NSMutableString alloc] initWithString:@"hello world"];

[mulStr7 setString:@"qifdfdng"];

NSLog(@"mulStr7 = %@", mulStr7);

}

return0;

}