iOS 字符串截取、替换、修饰

/* To avoid breaking up character sequences such as Emoji, you can do:
    [str substringFromIndex:[str rangeOfComposedCharacterSequenceAtIndex:index].location]
    [str substringToIndex:NSMaxRange([str rangeOfComposedCharacterSequenceAtIndex:index])]
    [str substringWithRange:[str rangeOfComposedCharacterSequencesForRange:range]
*/
- (NSString *)substringFromIndex:(NSUInteger)from;
- (NSString *)substringToIndex:(NSUInteger)to;
- (NSString *)substringWithRange:(NSRange)range;                // Use with rangeOfComposedCharacterSequencesForRange: to avoid breaking up character sequences

1、通过下标获取字符串

NSString * str = @"12345abcde";
NSString *logStr = [str substringFromIndex:6]; //从字符串下标为 6 的开始，截止字符串末尾

NSString * str = @"12345abcde";
NSString *logStr = [str substringToIndex:3]; //从字符串开始，截止字符串下标为 3 

/**
typedef struct _NSRange {
    NSUInteger location;
    NSUInteger length;
} NSRange;

typedef NSRange *NSRangePointer;

NS_INLINE NSRange NSMakeRange(NSUInteger loc, NSUInteger len) {
    NSRange r;
    r.location = loc;
    r.length = len;
    return r;
}
*/

NSString * str = @"12345abcde";
NSString *logStr = [str substringWithRange:NSMakeRange(2, 4)]; //从下标为2开始，截取长度为4的字符串

2、匹配查找字符串

 NSString * str = @"12345abcde";
 NSRange *logRange = [str rangeOfString:@"ab"]; //返回匹配到字符串的起始下标及长度

3、分割字符串

NSString * str = @"12345abcde";
NSArray *logArr = [str componentsSeparatedByString:@"a"]; //以a为分隔符，返回分割后的字符串数组
//数组元素拼接为字符串
NSString *toStr = [logArr componentsJoinedByString:@","];
//toStr  12345,bcde

 4、字符串替换

NSString *str = @"18888888888";
NSString *logString = [str stringByReplacingCharactersInRange:NSMakeRange(3, 4) withString:@"****"]; //隐藏手机号中间四位数
NSLog(@"%@",logString);//输出结果为188****8888
4 NSString *content = @"1&2&3&4&5&6";
5 NSString *replaceStr = [content stringByReplacingOccurrencesOfString:@"&" withString:@","];//用 , 替换 &
6 DebugLog(@"结果：%@",replaceStr);//输出结果 1,2,3,4,5,6

5、字符串大小写转换

/**
/* The following three return the canonical (non-localized) mappings. They are suitable for programming operations that require stable results not depending on the user's locale preference.  For locale-aware case mapping for strings presented to users, use the "localized" methods below.
*/
@property (readonly, copy) NSString *uppercaseString;
@property (readonly, copy) NSString *lowercaseString;
@property (readonly, copy) NSString *capitalizedString;
*/
NSString *str1 = @"abcdef123";
NSString *str2 = @"QWER456";
//字符串的英文字符由小写转换成大写
NSString *bigStr = [str1 uppercaseString];
NSLog(@"%@",bigStr); //输出结果为    ABCDEF123
//字符串的英文字符由大写转换为小写
NSString *smallStr = [str2 lowercaseString];
NSLog(@"%@",smallStr);//输出结果为  qwer456
//字符串的首字母改为大写
NSString *FirstletterbiggerStr = [str1 capitalizedString];
NSLog(@"%@",FirstletterbiggerStr);//输出结果为Abcdef123

6、字符串部分上色、修改样式

NSString *Str = @"我自愿加入原创者联盟";
NSMutableAttributedString *MutableStr = [[NSMutableAttributedString alloc] initWithString:Str];
[MutableStr addAttribute:NSForegroundColorAttributeName value:[UIColor grayColor] range:NSMakeRange(0, 5)];
//同样如果是改变字符串中某段字体的大小可以这样写：
[MutableStr addAttribute:NSFontAttributeName value:[UIFont SystemFontOfSize:28] range:NSMakeRange(5, 5)];