NSMutableString的一个报错

let address = "http://www.baidu.com/?cevent=imt%2Fguide%252525252525252F"
let address2 = "http://www.baidu.com/?cevent=imt%2Fguide%2525252525252521"
let bodyString=NSMutableString()


bodyString.appendFormat("\(address)")

上面的代码执行时会报错,只是因为 address 最后一个 F,如果改成数字,竟然就没错了,这是什么道理?

2016-04-05 19:014