swift学习笔记_iOS开发（一）

//打印
print("Hello world and how are you")

//定义常量和变量 let常量 var变量
let a=3
print(a)
var t=2
print(t)
t=4
print(t)

//在string中加入数值
//用法一：
let label="hello"
let width=2
let labeltime=label + String(width)
print(labeltime)
//用法二：
let appleNumber=3
let orangeNumber=5
let appleSummary="appleSummary is \(appleNumber)"
let fruitSummary="fruitSummary is \(appleNumber + orangeNumber)"
print(appleSummary)
print(fruitSummary)

//定义数组
var shoppingList=["catfish","water","tulips","blue paint"]
print(shoppingList)
//通过index改变其中的元素
shoppingList[2]="bottle of water"
print(shoppingList)
//通过key改变其中元素
var occupations = ["Malcolm":"Captain", "Kaylee":"Mechanic"]
print(occupations)
occupations["Jayne"]="Public Relations"
print(occupations)
occupations["Malcolm"]="Leader"
print(occupations)

//用初始化的方法
//定义空的数组
let emptyArray=[String]()
//定义空的字典
let emptyDictionary=[String : Float]()
//如果他们的数据类型在在之前已经确定，那么就可以用一下方法写空
shoppingList=[]
occupations=[:]
//另：数组和字典的区别－数组只需要把数据放进去就行，而字典需要key做索引

//用if，switch写条件判断语句；用for－in，for，while和repeat－while来写循环语句
let individualScores=[77,39,82,44,63]
var teamScore=0
for score in individualScores{
if score > 50{
teamScore += 3
}
else{
teamScore += 1
}
}

//在if语句中条件必须是布尔型的否则会报错这
if teamScore{   //报错:int 不是 Boolean Type
//。。。
}

//