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,const
char * 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,const
char * 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,const
char * 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;
}