去空格

1.去掉两端的空格

[str stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]

2.去掉多余的空格

NSString *str = @"    this     is a    test    .   ";

    NSCharacterSet *whitespaces = [NSCharacterSet whitespaceCharacterSet]; //获取空格字符
    NSArray *parts = [str componentsSeparatedByCharactersInSet:whitespaces];
//等同于NSArray *parts = [str componentsSeparatedByString:@" "];
    NSPredicate *noEmptyStrings = [NSPredicate predicateWithFormat:@"SELF != ''"];
    NSArray *filteredArray = [parts filteredArrayUsingPredicate:noEmptyStrings];
    str = [filteredArray componentsJoinedByString:@" "];

3.去掉所有空格

[str stringByReplacingOccurrencesOfString:@" " withString:@""]