Swift 3.0:
vowels.index(of:"F")
for (i, vowel) in vowels.enumerated() {}
vowels.index(of:"F")
for (i, vowel) in vowels.enumerated() {}
2017-02-25
替换已改为 str.replacingOccurrences(of: "Hi" , with: "Morning")
2017-02-25