去掉字符串中所有的空格：

//stringByReplacingOccurrencesOfString字符串替换方法，将空格替换为空
NSString *string = [sourceString stringByReplacingOccurrencesOfString:@" " withString:@""];

去掉左右两边的空格

//去掉左右两边的空格
NSString *string = [sourceString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
//去掉左右两边的空格和换行
NSString *string = [sourceString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];