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The Patlak--Keller--Segel model can be used to model the nonlocal aggregation phenomena in the collective motion of cells or the evolution of the density of bacteria by chemotaxis. We consider the free boundary value problem for the Patlak--Keller--Segel model with homogeneous nonlinear degenerate diffusion in the present paper, which can be used to simulate the congested phenomena and the dynamical behaviors of cell motion with finite total mass and compactly supported density distribution. For the subcritical case, we prove that the cell density function exists globally in time and tends to the corresponding steady-state at an exponential time rate due to the balance between the nonlinear diffusion effect and nonlocal aggregation. For the supercritical case, we show that the global solution for the cell density exists and converges algebraically in time to the Barenblatt solution of the corresponding porous media equation due to the diffusion dominating mechanism. This provides a different viewpoint on the dynamical behaviors of the congested phenomena subject to the combined influences of nonlinear diffusion and nonlocal aggregation. [ABSTRACT FROM AUTHOR]