iOS基础：String常用方法

一、NSString常用方法

//将c字符串转为oc字符串

+ (nullableinstancetype)stringWithCString:(constchar
*)cString encoding:(NSStringEncoding)enc;
+ (nullableinstancetype)stringWithUTF8String:(constchar
*)nullTerminatedCString;
//将oc字符串转为c字符串

char * cStr = [str3UTF8String];
//查找字符串

- (NSRange)rangeOfString:(NSString
*)searchString;
//获取子字符串

- (NSString *)substringFromIndex:(NSUInteger)from;
- (NSString *)substringToIndex:(NSUInteger)to;
- (NSString *)substringWithRange:(NSRange)range;
//比较字符串

- (NSComparisonResult)compare:(NSString *)string;

NSOrderedAscending==> 小于

NSOrderedDescending ==> 大于

NSOrderedSame ==> 相等

- (BOOL)isEqualToString:(NSString
*)aString;
//字符串前后缀

- (BOOL)hasPrefix:(NSString
*)str;
- (BOOL)hasSuffix:(NSString
*)str;
//字符串与字符

-(unichar)characterAtIndex:(NSUInteger)index;
NSUInteger length = [strlength];
//字符串分隔与拼接

- (NSArray<NSString
*> *)componentsSeparatedByString:(NSString *)separator;
- (NSArray<NSString
*> *)componentsSeparatedByCharactersInSet:(NSCharacterSet *)separator
NS_AVAILABLE(10_5,2_0);

二、NSMutableSting常用的方法

//覆盖
- (void)setString:(NSString *)aString;
//插入
- (void)insertString:(NSString *)aString
atIndex:(NSUInteger)loc;

//增
- (void)appendString:(NSString
*)aString;
- (void)appendFormat:(NSString
*)format, ...

//删

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

urlStr = [urlStr stringByReplacingOccurrencesOfString:@"thumbnail"
withString:@"bmiddle"];