#import UIKit 和#import <UIKit/UIkit.h>的区别
- #import UIKit
是去项目的Build Setting中的Header Search Paths中寻找
- #import <UIKit/UIKit.h>
是去项目的Build Setting中的Framework Search Paths中寻找
自定义操作符--Swift
操作符分为三种类型
- 前缀操作符：prefix
extension Int {
static prefix func --(num: Int) -> Int {
return num - 1
}
}
let a = 3
let b = --a
print(b)
# b = 2
- 中缀操作符：infix
extension Double {
static func +=(left: Double, right: Double) -> Double {
return (left + right) * right
}
}
let a: Double = 2
let b: Double = 4
let c = a += b
print(c)
#c = 24.0
- 后缀操作符：postfix
extension Float {
static postfix func --(num: inout Float) -> Float {
let numTmp = num
num = numTmp - 1
return numTmp
}
}
var a: Float = 7.0
let b = a--
print(a)
#a = 6.0
print(b)
#b = 7.0
