NSMutableString可变字符串

初始化

NSMutableString *s1 = [NSMutableString stringWithCapacity:0];//通过设置空间来创建字符串对象；

NSMutableString *s3 = [@"123" mutableCopy];

添加字符串

[s1 appendFormat:@"abc"];

NSString *s2 = @"abc"

[s1 appendString:s2];

[s1 stringByAppendingString:@"123"];

插入字符串

[s1 insertString:@"123" atIndex:1];//atIndex后面加NSUInteger格式

重置字符串

[s1 setString:@"abc defg"];

删除部分字符

[s1 deleteCharactersInRange:NSMakeRange(2,3)];

改变部分字符

[s1 replaceCharactersInRange:NSMakeRange(1,2) withString:@"ABC"];