The current deployment target does not support automatic _ weak references

When downloading and running a demo, the following error occurs: "The current deployment target does not support automated _ weak references". Find the following method:

Xcode versions earlier than 4.2 do not support arc.

There are also requirements for the operating system: Mac OS X v10.6 or v10.7 (64-bit applications), ios4 or ios5. Note: Mac OS X v10.6 and ios4 do not support weak references (weak references: What is weak references ).

Xcode 4.2 provides a tool named "convert to objective-C automatic reference counting". Under the edit-> convert menu, you can automatically convert the old code using manual reference counting into new code using arc (for example, removing the call to retain and release ).

Or upgrade the system version. Project-> Info-> IOS deployment target

Because the demo uses arc, you only need to change it.DeploymentTarget version.

Reference: http://www.xuebuyuan.com/2037668.html