[Objective-C] 007_Foundation框架之NSString与NSMutableString

　　在Cocoa Foundation中的NSString和NSMutableString类，为我们提供了Unicode字符串的支持，NSString和NSMutableString类最大的区别是：NSString--创建赋值以后该字符串的内容与长度不能在动态的更改，除非重新给这个字符串赋值。NSMutableString--创建赋值以后可以动态在该字符串上更改内容与长度。下面是NSString和NSMutableString类的一些常用操作。

1.NSString 创建常量字符串。

NSString *str = @"我是一个字符串 -- This is a String!";

2.NSString  创建空字符，并赋值

NSString *str = [[NSString alloc] init];
str = @"www.babybus.com";
NSLog(@"str内容:%@",str);
[astring release];
NSString *str2 = [[NSString alloc] initWithString:@"www.babybus.com"];
NSLog(@"str2:%@",str2);
[str2 release];

//用标准c创建字符串:initWithCString方法
char *c_str = "www.babybus.com"
NSString *str3 = [[NSString alloc] initWithCString:c_str];
NSLog(@"str3:%@",str3);
[str3 release];

//创建格式化字符串:占位符
NSString *str4 = [[NSString alloc] initWithString:[NSString stringWithFormat:@"宝宝巴士拥有%d用户了",70000000]];
NSLog(@"str4:%@",str4);
[str4 release];

//从文件初始化字符串
NSString *path = [[NSBundlemainBundle] pathForResource:@"test" ofType:@"text"];
NSString *str = [[NSString alloc] initWithContentsOfFile:path];
NSLog(@"str:%@",str);
[str release];

3.NSString 内容写入文件

//获取Documents
NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES) firstObject];
//路径拼接
NSString *fielPath = [documentsPath stringByAppendingPathComponent:@"str.txt"];

NSString *str = [[NSString alloc] initWithString:@"www.babybus.com"];
NSLog(@"str:%@",str);
[str writeToFile:fielPath atomically:YES encoding:NSUTF8StringEncoding error:nil];
[str release];

4.NSString 字符内容比较

NSString *str_1 = @"www.babybus.com";
NSString *str_2 = @"www.babybus.com";
BOOL result = [str_1 isEqualToString:str_2];
if (result) {
    NSLog(@"内容相同...");
}else {
    NSLog(@"不好意思，内容不同");
}

//NSOrderedSame判断两者内容是否相同
NSString *str_1 = @"www.babybus.com";
NSString *str_2 = @"www.babybus.com";
BOOL result = [str_1 compare:str_2] == NSOrderedSame;
NSLog(@"result:%d",result);

//NSOrderedAscending判断两对象值的大小(按字母顺序进行比较，str_2大于str_1为真)
NSString *str_1 = @"www.babybus.com";
NSString *str_2 = @"www.babybus.com";
BOOL result = [str_1 compare:str_2] == NSOrderedAscending;
NSLog(@"result:%d",result);

//NSOrderedDescending判断两对象值的大小(按字母顺序进行比较，str_2小于str_1为真)
NSString *str_1 = @"www.babybus.com";
NSString *str_2 = @"www.babybus.com";
BOOL result = [str_1 compare:str_2] == NSOrderedDescending;
NSLog(@"result:%d",result);

5.NSString 不考虑大小写内容比较

NSString *str_1 = @"WWW.BABYBUS.COM";
NSString *str_2 = @"www.babybus.com";
//NSCaseInsensitiveSearch:不区分大小写比较  NSLiteralSearch:进行完全比较,区分大小写  NSNumericSearch:比较字符串的字符个数，而不是字符值。
BOOL result = [str_1 compare:str_2 options:NSCaseInsensitiveSearch | NSNumericSearch] == NSOrderedSame;
NSLog(@"result:%d",result);

6.NSString 输出大写或者小写字符串

NSString *str_1 = @"www.babybus.com";
NSString *str_2 = @"Good babybus";
NSLog(@"str_1:%@",[str_1 uppercaseString]);//大写
NSLog(@"str_2:%@",[str_2 lowercaseString]);//小写
NSLog(@"str_2:%@",[str_2 capitalizedString]);//首字母大小

7.NSString 查找字符串是否包含其它字符串

NSString *str_1 = @"www.babybus.com";
NSString *str_2 = @"babybus";
NSRange range = [str_1 rangeOfString:str_2];
if (range.location != NSNotFound) {
    NSLog(@"找到了%@",str_2);
}

8.NSString 截取字符串

//substringToIndex: 从字符串的开头一直截取到指定的位置，但不包括该位置的字符
NSString *str_1 = @"www.babybus.com";
NSString *str_2 = [str_1 substringToIndex:3];
NSLog(@"string2--->:%@",str_2);

//substringFromIndex: 以指定位置开始（包括指定位置的字符），并包括之后的全部字符
NSString *str_1 = @"www.babybus.com";
NSString *str_2 = [str_1 substringFromIndex:3];
NSLog(@"string2--->:%@",str_2);

//substringWithRange: 按照所给出的位置，长度，任意地从字符串中截取子串
NSString *str_1 = @"www.babybus.com";
NSString *str_2 = [str_1 substringWithRange:NSMakeRange(0, 4)];
NSLog(@"string2--->:%@",str_2);

9.NSString 是否以某一字符串开头或者结尾

NSString *str = @"http://wwww.babybus.com";
if([String1 hasPrefix:@"http://"] == 1) {
    NSLog(@"http://开头") ;
}

if([String1 hasSuffix:@"com"] == 1) {
    NSLog(@"com结尾") ;
}

10.NSString 获取后缀名

NSString *Path = @"User/SuperDo/string.txt";
NSLog(@"Extension:%@",[Path pathExtension]);

11.NSString 获取拓展路径

NSString *Path = @"User/SuperDo/str.txt";
NSString *absolutePath = [Path stringByExpandingTildeInPath];
NSLog(@"absolutePath:%@",absolutePath);
NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);

12. NSMutableString 字符串拼接

//末尾拼接
NSMutableString *str_1 = [[NSMutableString alloc] initWithString:@"www.babybus.com"];
[str_1 appendString:@",good"];
[str_1 appendFormat:@"go --------->"];
NSLog(@"String1:%@",str_1);
//在指定位置插入
NSMutableString *str = [[NSMutableString alloc] initWithString:@"www.babybus.com"];
[str insertString:@"Hi! " atIndex:0];
 NSLog(@"str:%@",str);

13.NSMutableString  替换字符串

NSMutableString *str = [[NSMutableString alloc] initWithString:@"www.babybus.com is NSMutableString"];
[str replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];
NSLog(@"str:%@",str);

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转载自【宝宝巴士SuperDo团队】 原文链接: http://www.cnblogs.com/superdo/p/4584355.html