最近临时转做app开发了，采用了swift语言开发，这里简要记录几点开发过程中遇到的难点
- 1.函数做参数和变量
//返回值无参
var callback : (() -> Void)?
//闭包默认是不可逃逸的，逃逸闭包需要像这样被标记@escaping
func setData(call: @escaping () -> Void)
{
callback = call
}
//带参返回
var callback: ((String) -> Int)?
func setData(call: @escaping (String) -> Int)
{
callback = call
}
- 2.回调js时参数有xml内容的情况
let fileUrl:URL = URL(fileURLWithPath: path)
do {
var content:String = try String(contentsOf: fileUrl, encoding: .utf8)
print(content)
//xml要去掉换行符，否则会报EOF的语法错误
content = content.trimmingCharacters(in: .whitespacesAndNewlines)
content = content.replacingOccurrences(of: "\r", with: "")
// \\n --> json中不能有换行符
content = content.replacingOccurrences(of: "\n", with: "")
content = content.replacingOccurrences(of: "\'", with: "\\\'")
content = content.replacingOccurrences(of: "\"", with: "\\\'")
//json字符串
let reVal:String = "{\"name\":\"\(fileUrl.lastPathComponent)\", \"content\":\"\(content)\"}"
let jsStr = "resolvePromise('\(promiseId)','\(reVal)','')"
webView.evaluateJavaScript(jsStr) { (any, error) in
if(error != nil)
{
print(error!)
}
}
} catch {
print("read file error at", path)
}
对应上面读取的xml传给js时报的错误：
//json的key和value要用引号包含
Error Domain=WKErrorDomain Code=4 "A JavaScript exception occurred" UserInfo={WKJavaScriptExceptionLineNumber=1, WKJavaScriptExceptionMessage=SyntaxError: Unexpected token '<', WKJavaScriptExceptionColumnNumber=0, WKJavaScriptExceptionSourceURL=http://xxxxxxxxxx, NSLocalizedDescription=A JavaScript exception occurred}
或
//不能有换行符
WKJavaScriptExceptionMessage=SyntaxError: Unexpected EOF