canlanyangg的博客

a != nil ? a! : b 是 a ?? b 的缩写llet defaultColorName = "red"var userDefinedColorName: String?   // defaults to nil var colorNameToUse = userDefinedColorName ?? defaultColorName// userDefinedC

let anotherPoint = (2,0)switch anotherPoint {     case (let x , 0):             print("on the x-axis with an x value of \(x)")     case (0 , let y):             print("on the y-axis with an

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(loadDdataConnect) name:kloginSuccess object:nil];[[NSNotificationCenter defaultCenter] removeObserver:self];