iOS NSString 截取字符串

1. rangeOfString:截取指定字符串的長度；

2. substringToIndex:7：截取從0 索引到指定索引（7）長度的字符串
3. substringFromIndex:9：截取從指定索引（9）到末尾長度的字符串
4. NSRange range = NSMakeRange(0,7);截取從指定索引（0）到指定（7）長度的字符串
5. substringWithRange:range：截取從指定索引（0）到指定（7）長度的字符串
6. isEqualToString:@"p://www"：比較字符串包含關系，區分大小寫
7. stringWithFormat:格式化字符串。



void findSubString(){
    NSString *filename = @"config.ini";
    NSString *escapedPath = @"/Users/config.ini";

    //在escapedPath中查找filename
    //NSRange iStart = [escapedPath rangeOfString :filename];
    NSRange iStart = [escapedPath rangeOfString: filename options:NSCaseInsensitiveSearch];
   // NSLog(@"iStart length is %@:",iStart.length);
   // NSLog(@"iStart location is %@:",iStart.location);
    if (iStart.length > 0){
        //獲取從escapedPath開始位置到iStart.location-1長度的子字符串
        NSString *subStr = [escapedPath  substringToIndex:iStart.location-1];
        NSLog(@"subStr:%@",subStr);

        //獲取從escapedPath從iStart.location+1開始到末尾的子字符串
        NSString *extension  = [escapedPath  substringFromIndex:iStart.location];
        NSLog(@"extension:%@",extension);

        NSString *url = @"http://www.sevenuc.com";
        NSRange range = NSMakeRange(3,7);
        NSString* prefix = [url substringWithRange:range];
        NSLog(@"prefix is:%@",prefix);
        if([prefix isEqualToString:@"p://www"])
        {
            NSLog(@"prefix is equal %@",prefix);
        }
        else {
            NSLog(@"prefix is not equal %@",prefix);
        }
        //獲取url從0開始共7個字符的子字符串
        if ( [prefix isEqualToString:@"http://"] )
            NSLog(@"http prefix found");
        }
}