NSString几个函数

第一、判断是否包含前缀于后缀

NSString *str=@"hello andy yang";

if([str hasPrefix:@"hello"])

{

NSLog(@"the prefix is hello");

}

if([str hasSuffix:@"yang"])

{

NSLog(@"the suffix is yang");

}

第二、NSRange

typedefstruct _NSRange {

NSUInteger location;  //开始位置

NSUInteger length;  //长度

} NSRange;

NSRange的定义：

NSRange range2;

range2.location = 17;

range2.length = 4;

NSLog(@"%lu and  %lu",range2.location,range2.length);

//用NSMakeRange来初始化

NSRange rang1=NSMakeRange(12, 23);

NSLog(@" %lu and %lu",rang1.location,rang1.length);

第三、 rangeOfString函数的使用

NSRange range;

range=[str rangeOfString:@"andy"];

NSLog(@"%lu and  %lu",range.location,range.length);

第四、compare实现函数的比较

NSString *str1=@"AA";

NSString *str2=@"aBB";

if ([str2 compare:str1])

{

NSLog(@"%@ is larger than %@",str1,str2);

}else

{

NSLog(@"%@ is larger than %@",str2,str1);

}

第五、NSMutabelString 继承自NSString

- (void)appendString:(NSString *)aString;

- (void)appendFormat:(NSString *)format, ... NS_FORMAT_FUNCTION(1,2);

sample code：

NSMutableString
*str=[
NSMutableString

stringWithCapacity
:
12
];

[str appendString:@"hello"];

NSLog(@"str is %@",str);

[str appendFormat:@" andy yang %d",11];

NSLog(@"str is %@",str);

- (void)deleteCharactersInRange:(NSRange)range; 删除字符串

NSMutableString *str1=[NSMutableString stringWithFormat:

@"hello what is your name?"];

NSRange range;

range=[str1 rangeOfString:@"what"];

NSLog(@"start is %lu,length is %lu",range.location,range.length);

[str1 deleteCharactersInRange:range];

NSLog(@"str is %@",str1);