iOS 字符串常用处理方法

一、字符串截取

1.截取前a个字符串
[str substringToIndex:a]; 
2.从第a个截取到最后
[str substringFromIndex:a];
3.截取最后a个字符
[str substringFromIndex: str.length-a];
4.截取两个字符之间的字符串
NSRange start = [string rangeOfString:@"["];
NSRange end = [string rangeOfString:@"]"];
NSString *sub = [string substringWithRange:NSMakeRange(start.location, end.location-start.location+1)];

二、判断字符串是否包含某个字符串

if([str rangeOfString: str1].location != NSNotFound){
  NSLog(@“str包含str1”);
}else{
 NSLog(@“str不包含str1”);
}

三、字符串转数组&&数组转字符串

1、
NSArray *arr = [str componentsSeparatedByString:@","];
2、
NSString *string = [array componentsJoinedByString:@","];