要删除前导和尾随空格:

To remove leading and trailing whitespaces:

let trimmedString = string.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())

斯威夫特 3/斯威夫特 4:

Swift 3 / Swift 4:

let trimmedString = string.trimmingCharacters(in: .whitespaces)