1. Wish
Wish is used when the speaker wants reality to be different, to be exactly the opposite.
Verb forms similar to those in conditional sentences are used.
Wish is followed by a noun clause.
A wish about the future: I wish she would tell me --> Verb form in “true” sentence: She will not tell me.

2. Wish
A wish about the present: I wish she knew French --> Verb form in “true” sentence: I don’t know French.
A wish about the past: I wish John had come --> Verb form in “true” sentence: John didn’t come.
Would is used to indicate that the speaker wants something to happen in the future. The wish may or may not come true (be realized), e.g. It is raining. I wish it would stop --> I want it to stop raining.

3. Wish Like + a noun object: It looks like rain.
As if/ as though + a clause: It looks as if it is going to rain.
Usually the idea following as if/as though is “untrue.” --> verb usage is similar to that in conditional sentences, e.g. He has met her (‘true’ statement) vs He acted as though he had never met her.