Wouldn't an unconditional basic income lead to an inflation that negates its effect?
Theoretically basic income might have a tendency to increase inflation. But that largely depends on how much is the basic income provided. Usually, the idea of basic income itself means that it is 'basic' and is just sufficient for a subsistence. With such an income level, the problem of inflation does not crop up really. 
However, basic income might have other serious problems with crowding out due to large government spending and the disincentive to work and hence loss of productivity. 

Even if we suppose, there is a large basic money disbursement which can cause inflation, then I think it should not be unconditional. Usually, such plans are in the form of guaranteed employment programs, buying of ration from designated stores and many more measures. However, I still feel these measures are not for tackling inflation rather the disincentive to work.