ios 判断字符串是否全部空格

+ (BOOL) isEmpty:(NSString*) str {

     

    if(!str) {

        returntrue;

    }else{

        //A character set containing only the whitespace characters space (U+0020) and tab (U+0009) and the newline and nextline characters (U+000A–U+000D, U+0085).

        NSCharacterSet*set = [NSCharacterSetwhitespaceAndNewlineCharacterSet];

         

        //Returns a new string made by removing from both ends of the receiver characters contained in a given character set.

        NSString*trimedString = [str stringByTrimmingCharactersInSet:set];

         

        if([trimedString length] == 0) {

            returntrue;

        }else{

            returnfalse;

        }

    }

}