---
title: "if(_:then:else:name:)"
framework: metalperformanceshadersgraph
role: symbol
role_heading: Instance Method
path: "metalperformanceshadersgraph/mpsgraph/if(_:then:else:name:)"
---

# if(_:then:else:name:)

Adds an if-then-else operation to the graph.

## Declaration

```swift
func `if`(_ predicateTensor: MPSGraphTensor, then thenBlock: @escaping MPSGraphIfThenElseBlock, else elseBlock: MPSGraphIfThenElseBlock?, name: String?) -> [MPSGraphTensor]
```

## Parameters

- `predicateTensor`: Tensor must have a single scalar value, used to decide between then/else branches
- `thenBlock`: If predicate is true operations in this block are executed
- `elseBlock`: If predicate is false operations in this block are executed
- `name`: Name of operation

## Return Value

Return Value Results If no error, the tensors returned by user. If not empty, user must define both then/else block, both should have same number of arguments and each corresponding argument should have same elementTypes.