NSMutableString 可变字符串对象
1.字符串对象本身不可以被修改
2.NSMutableString 是NSString的子类继承NSString
3.创建可变字符串对象 字符串对象本身可以被修改
4.可变字符串对象可以直接调用不可变字符串对象的方法
创建一个可变字符串
1.直接创建
NSMutableString *mstr ;
[mstr setString:str3];
NSLog(@"mstr = %@", mstr);
2.由不可变字符串转换为可变字符串
NSString *str3 = @"This is string A";
NSString *str4 = @"This is string B";
NSMutableString *mstr ;
mstr = [NSMutableString stringWithString:str3];
NSLog(@"mstr = %@", mstr);
可变字符串的操作
//在指定位置增加字符串
//- (void)insertString:(NSString *)aString atIndex:(NSUInteger)loc;
[str1 insertString:@" welcome" atIndex:5];
NSLog(@"str1 = %@",str1);
//删除指定范围内的字符
//- (void)deleteCharactersInRange:(NSRange)range
[str1 deleteCharactersInRange:NSMakeRange(6, 3)];
NSLog(@"str1 = %@",str1);
//在字符串末尾追加字符串
//- (void)appendString:(NSString *)aString;
[str1 appendString:@" baidu"];
NSLog(@"str1 = %@",str1);
//格式化追加字符串
//- (void)appendFormat:(NSString *)format, ... NS_FORMAT_FUNCTION(1,2);
[str1 appendFormat:@"%d%s",123,".com"];
NSLog(@"str1 = %@",str1);
//替换
[mstr replaceCharactersInRange:NSMakeRange(3, 4) withString: @" hello "];
NSLog(@"mstr = %@",mstr);
//查找
NSRange range1 = [mstr rangeOfString:@"A"];
NSLog(@"range1.location = %lu ,range.length = %lu ", range1.location, range1.length);